Free Study Material of Information & Communication Technology
for CBSE UGC NET Paper I
Computer: A computer is a truly amazing machine that performs a specified sequence of operations as per the set of instructions (known as programs) given on a set of data (input) to generate desired information (output ).
A complete computer system consists of four parts:
- Hardware: Hardware represents the physical and tangible components of the
- Software: Software is a set of electronic instructions consisting of complex codes (Programs) that make the computer perform
- User: The computer operators are known as
- Data: Consists of raw facts, which the computer stores and reads in the form of
Functionalities of a computer
Any digital computer carries out five functions in gross terms:
- Takes data as input.
- Stores the data/instructions in its memory and use them when required.
- Processes the data and converts it into useful information.
- Generates the output
- Controls all the above four steps.
The following features characterize this electronic machine:
|ü Speed||ü Flexibility|
|ü Accuracy||ü Low cost|
|ü Storage and Retrieval
|ü Repeated Processing Capabilities
Applications of Computer
Following list are various applications of computers in today’s arena.
Following are the main five generations of computers:
|S. No.||Generation & Description|
|1||First Generation (1946-1959) – Vacuum tube based|
|2||Second Generation (1959-1965) – Transistor based|
|3||Third Generation (1965-1971) – Integrated Circuit based|
|4||Fourth Generation (1971-1980) – VLSI microprocessor based|
|5||Fifth Generation (1980-onwards) – ULSI microprocessor based|
Computer hardware consists of the following components:
- CPU (Central Processing Unit): CPU is considered as the brain of the computer. It performs all types of data processing operations, stores data, intermediate results and instructions (program).It controls the operation of all parts of
Fig: The relationship between different hardware Components
[A] CPU itself has following three components:
- ALU (Arithmetic Logic Unit): When the control unit encounters an instruction that involves mathematical calculation or decision/logic, it passes the control to the second component, i.e., the arithmetic logic unit (ALU). The ALU includes a group of registers – memory locations built directly into the CPU – that are used to hold data that are being processed by the current
- Registers: The register is the smallest high-speed storage area in the CPU. All data must be represented in a register before it can be
- Control Unit: This unit controls the operations of all parts of computer but does not carry out any actual data processing operations
[B] Primary memory consists of mainly two types of memories:
1. Random Access Memory (RAM): RAM is the internal memory of the CPU for storing data, program and program result. It is read/write memory which stores data until the machine is working. As soon as the machine is switched off, data is erased.
RAM is volatile, i.e. data stored in it is lost when we switch off the computer or if there is a power failure. Hence a backup uninterruptible power system (UPS) is often used with computers. RAM is small, both in terms of its physical size and in the amount of data it can hold.
There are mainly three types of RAM available:
- Dynamic Random Access Memory (DRAM): A type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed2 (reenergized) or it loses its contents. This type of memory is more
- Static Random Access Memory (SRAM): A type of memory that is faster and less volatile than DRAM, but requires more power and is more expensive. The term static is derived from the fact that it does not need to be refreshed like
- Synchronous Dynamic Random Access Memory (SDRAM): A type of DRAM that can run at much higher clock
2. Read Only Memory (ROM): The memory from which we can only read but can not write on it . This type of memory is non-volatile. The information is stored permanently in such memories during manufacture. A ROM, stores such instructions that are required to start a computer. This operation is referred to as bootstrap.
There are mainly three types of ROM available:
- MROM (Masked ROM): The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are known as masked ROMs which are
- EPROM (Erasable and Programmable Read Only Memory): The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this
- EEPROM (Electrically Erasable and Programmable Read Only Memory): The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 ms (milli second).
A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in a computer where data is to be processed and instructions required for processing are stored. The memory is divided into a large number of small parts called cells. Each location or cell has a unique address which varies from zero to memory size minus one.
Memory is primarily of three types –
- Cache Memory: It is a very high-speed semiconductor memory which can speed up CPU. It acts as a buffer between the CPU and main memory.
- Primary Memory/Main Memory: Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off.
- Secondary Memory: This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently.
1. Secondary Storage (External Storage Devices): Floppy diskettes, hard disk, tapes and optical disks come under the category of external storage devices or ancillary storage devices. These devices are very sensitive to environmental conditions (humidity and temperature) as well as to external magnetic fields and need to be stored.
- Floppy Disk: Floppy disks are primarily used on PCs. Information on a floppy disk is recorded in the magnetized states of particles of iron oxides evenly placed upon concentric circles known as Tracks.
- Hard Disk: It is a non-removable enclosed magnetic disk included in most PCs. It contains a stack of metal platters, each coated with iron oxide, that spin on a spindle and the entire unit is encased in a sealed chamber.
- Magnetic Tape: This is plastic tape, usually made of Mylar that is coated with iron oxide, thereby enabling the introduction (writing); retention (memory) and reading of magnetically recorded information. The best use of tape storage is for data that you do not use very often.
2. Peripherals: Peripheral devices are devices connected to the computer externally. If a peripheral device is disconnected, the computer will still be able to work; only functions performed by this peripheral device will not be available.
Mainly there are following types of peripheral devices:
A. Input Devices (How to tell it what to do): This unit makes a link between user and computer. The input devices translate the information into the form understandable by
- Keyboard- The most common and very popular input device which helps in inputting data to the computer.
- Mouse- Mouse is the most popular pointing device and cursor-control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed.
- Joy Stick- To move cursor position on a monitor screen. It is mainly used in Computer Aided Designing (CAD) and playing computer games.
- Light pen- It is used to select a displayed menu item or draw pictures on the monitor screen.
- Track Ball- Mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer can be moved.
- Scanner- A scanner allows you to scan printed material and convert it into a file format that may be used within the PC.
- Digitizer- It converts analog information into digital form.
- Microphone-Microphone is an input device to input sound that is then stored in digital form.
- Magnetic Ink Card Reader (MICR)-MICR input device is generally used in banks because of a large number of checks to be processed every day.
- Optical Character Reader (OCR)- OCR scans text optically character by character, converts them into a machine-readable code and stores the text on the system memory.
- Bar Code Reader- A device used for reading bar coded data (data in form of light and dark lines). Barcoded data is generally used in labeling goods, numbering the books.
- Optical Mark Reader(OMR)- A special type of optical scanner used to recognize the type of mark made by pen or pencil.
B. Output Devices: (How it shows you what it is doing) Output devices translate the computer’s output into the form understandable by
Monitors: Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels.
There are two kinds of viewing screen used for monitors.
- Cathode-Ray Tube (CRT): The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity, or resolution
- Flat- Panel Display: The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the
Printer: Printer is an output device, which is used to print information on paper.
- Impact Printers: The impact printers print the characters by striking them on the ribbon which is then pressed on the
- Non-Impact Printers: Non-impact printers print the characters without using ribbon. These printers print a complete page at a time so they are also called as Page Laser Printers, Inkjet Printers.
- Data: Data can be defined as a representation of facts, concepts or instructions in a formalized manner which should be suitable for communication, interpretation, or processing by human or electronic
- Information:- Information is organized or classified data which has some meaningful values for the receiver. Information is the processed data on which decisions and actions are
- Data Processing Cycle: Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness and add values for particular Data processing consists of basic steps input, processing and output.
These three steps constitute the data processing cycle.
- Input -Input data is prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data could be recorded on any one of several types of input medium, such as magnetic disks, tapes and so on.
- Processing – In this step input data is changed to produce data in a more useful form. For example, paychecks may be calculated from the time cards, or a summary of sales for the month may be calculated from the sales orders.
- Output – The result of the proceeding processing step are collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees.
Assembler: This language processor converts the program written in assembly language into machine language.
Interpreter: This language processor converts a HLL (High Level Language) program into machine language by converting and executing it line by line.
Compiler:-It also converts the HLL program into machine language but the conversion manner is different. It converts the entire HLL program in one go, and reports all the errors of the program along with the line numbers.
Classification of Computers:
Computers can be broadly classified by their speed and computing power:
|1||PC (Personal Computer)||It is a single user computer system having moderately powerful microprocessor.|
|2||WorkStation||It is also a single user computer system which is similar to personal computer but have more powerful microprocessor.|
|3||Mini Computer||It is a multi-user computer system which is capable of supporting hundreds of users simultaneously. Software technology is different from minicomputer.|
|4||Main Frame||It is a multi-user computer system which is capable of supporting hundreds of users simultaneously. Software technology is different from minicomputer.|
|5||Supercomputer||It is an extremely fast computer which can execute hundreds of millions of instructions per second.|
Following are the main memory storage units:
|1||Bit(Binary Digit)||A binary digit is logical 0 and 1 representing a passive or an active state of a component in an electric circuit.|
|2||Nibble||A group of 4 bits is called nibble.|
|3||Byte||A group of 8 bits is called byte. A byte is the smallest unit which can represent a data item or a character. (1 byte = 8 bits)|
|4||Word||A computer word, like a byte, is a group of fixed number of bits processed as a unit which varies from computer to computer but is fixed for each computer. The length of a computer word is called word-size or word length and it may be as small as 8 bits or may be as long as 96 bits. A computer stores the information in the form of computer words.|
Few higher storage units are following:
|1||Kilobyte (KB)||1 KB = 1024 Bytes|
|2||Megabyte(MB)||1 MB = 1024 KB|
|3||GigaByte (GB)||1 GB = 1024 MB|
|4||TeraByte (TB)||1 TB = 1024 GB|
|5.||PetaByte (PB)||1 PB = 1024 TB|
Software: software represents the set of programs that govern the operation of a computer system and make the hardware run. There are two types of software
- System Software: The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufactures. System software serves as the interface between hardware and the end users. Examples: Operating System, Compilers, Interpreter, Assembler
- Application Software: It is the set of programs necessary to carry out operations for a specified application
Application software can subdivide into three categories:
|Word Processing||A package that process textual matter and creates organized and flawless documents.|
|Spreadsheets||An electronic spreadsheet is a program that accepts data in a tabular form and allow users to manipulate , calculate, analyze data in the desired manner.|
|Database Management Systems||DBMS is a package that can handle and manage bulk of stored data.|
|Desktop Publishing Software||Handles page layout by combining the functions of a traditional typesetter and a layout artist.|
|Graphics, Multimedia and Presentation applications||Application software that manipulates images is known as Graphics software.|
- Utilities: Utilities are those application programs that assist the computer by performing housekeeping functions like backing up disk or scanning viruses etc.
|Text Editor||Program is used for creating, editing text files.|
|Backup Utility||Program facilities the backing-up of disk.|
|Compression Utility||Large files can be compressed so that it takes less storage area.|
|Disk Defragmentor||It speeds up disk access by rearranging the files and free space on your computer.|
|Antivirus Software||It scans yours disk for viruses and removes them if any virus is found.|
C. Customized Software: This type of software is tailor-made software according to a user’s requirement.
When we type some letters or words, the computer translates them in numbers as computers can understand only numbers. A computer can understand positional number system where there are only a few symbols called digits and these symbols represent different values depending on the position they occupy in the number.
A value of each digit in a number can be determined using
- The digit
- The position of the digit in the number
- The base of the number system (where base is defined as the total number of digits available in the number system).
- Decimal Number System: The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands and so
- Binary Number System: Uses two digits, 0 and 1, also called base 2 number system . Each position in a binary number represents a 0 power of the base (2). Last position in a binary number represents a x power of the base (2).
- Octal Number System: Uses eight digits, 0,1,2,3,4,5,6,7, also called base 8 number system, Each position in an octal number represents a 0 power of the base (8).
- Hexadecimal Number System: Uses 10 digits and 6 letters, 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. Letters represents numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15. Also called base 16 number system .Each position in a hexadecimal number represents a 0 power of the base (16).
There are many methods or techniques which can be used to convert numbers from one base to another.
We’ll demonstrate here the following
- Decimal to Binary System
- Binary to Decimal
Decimal to Binary System
Step 1 – Divide the decimal number to be converted by the value of the new base.
Step 2 – Get the remainder from Step 1 as the rightmost digit (least significant digit) of new base number.
Step 3 – Divide the quotient of the previous divide by the new base.
Step 4 – Record the remainder from Step 3 as the next digit (to the left) of the new base number.
Repeat Steps 3 and 4, getting remainders from right to left, until the quotient becomes zero in Step 3. The last remainder thus obtained will be the most significant digit (MSD) of the new base number.
Decimal Number: (29)10
Calculating Binary Equivalent:
|Step 1||29 / 2||14||1|
|Step 2||14 / 2||7||0|
|Step 3||7 / 2||3||1|
|Step 4||3 / 2||1||1|
|Step 5||1 / 2||0||1|
As mentioned in Steps 2 and 4, the remainders have to be arranged in the reverse order so that the first remainder becomes the least significant digit (LSD) and the last remainder becomes the most significant digit (MSD).
Decimal Number: (29)10 = Binary Number: (11101)2.
Binary to Decimal System
Step 1 – Determine the column (positional) value of each digit (this depends on the position of the digit and the base of the number system).
Step 2 – Multiply the obtained column values (in Step 1) by the digits in the corresponding columns.
Step 3 – Sum the products calculated in Step 2. The total is the equivalent value in decimal.
Binary Number: (11101)2
Calculating Decimal Equivalent:
|Step||Binary Number||Decimal Number|
|Step 1||(11101)2||((1 x 24) + (1 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10|
|Step 2||(11101)2||(16 + 8 + 4 + 0 + 1)10|
Binary Number: (11101)2 = Decimal Number: (29)10
Network: Computer Networks means an interconnected set of autonomous system that permits distributed processing to information.
- Sender Computer
- Sender equipment (Modem)
- Receiver Equipment(Modem)
- Receiver Computer
- Communication Channel ( Telephone Cables)
Classified on the basis of Geographical Coverage:
- Local Area Network (LAN): A local area network is a relatively smaller and privately owned network with the maximum span of 10 km.
- Metropolitan Area Network (MAN): MAN is defined for less than 50 Km and provides regional connectivity within a campus or small geographical area.
- Wide Area Network (WAN): A Wide Area Network (WAN) is a group Communication Technology, provides no limit of distance.
Types of Network
- Point to Point Network: When a packet is sent from one router to another intermediate router, the entire packet is stored at each intermediate router, stored there till the output line is free and then forwarded. A subnet using this principle is called point to point or packet switched network.
Topologies for a point to point Subnet
- Star: Each device has a dedicated point to point link only to a central controller, usually called a hub.
- Tree: A tree topology is a variation of a star.
- Ring: Each device has a dedicated point to point line configuration only with the two devices on either side of it.
- Bus: One long cable acts as a backbone to link all the devices in the network.
- Broadcast Networks: Broadcast networks have a single communication channel that is shared by all the machines on the network.
- Network Cables: Network cables are used to connect computers. The most commonly used cable is Category 5 cable RJ-45.
- Distributors: A computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work. The solution is to use a central body to which other computers, printers, scanners etc. can be connected and then this body will manage or distribute network traffic.
- Repeaters: A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distance.
- Bridge: A bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol (for example, Ethernet or token ring).
- Routers: A router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP’s network. Routers are located at gateways, the places where two or more networks connect.
- Internal Network Cards: Network card is a necessary component of a computer without which a computer cannot be connected over a network. It is also known as network adapter or Network Interface Card (NIC). Most branded computers have network card pre-installed. Network cards are of two types: Internal and External Network cards.
- External Network Cards: External network cards come in two flavours like Wireless and USB based. Wireless network card need to be inserted into the motherboard but no network cable is required to connect to network.
- Universal Serial Bus (USB): USB card are easy to use and connect via USB port. Computers automatically detect USB card and can install the drivers required to support the USB network card automatically.
- Modem (Modulator –DE Modulator): Modem is a device attached to computers that can convert digital signals to analog signals to analog signals and vice
An Operating system is a program, which acts as an interface between a user and the hardware.
Characteristics of Operating System:
- Memory Management — keeps tracks of primary memory i.e. what part of it is in use by whom, what part is not in use etc. and allocates the memory when a process or program requests it.
- Processor Management — allocates the processor(CPU) to a process and de-allocates processor when it is no longer required.
- Device Management — keeps track of all devices. This is also called I/O controller that decides which process gets the device, when, and for how much time.
- File Management — allocates and de-allocates the resources and decides who gets the resources.
- Security — prevents unauthorized access to programs and data by means of passwords and similar other techniques.
- Job accounting — keeps track of time and resources used by various jobs and/or users.
- Control over system performance — records delays between the request for a service and from the system.
- Interaction with the operators — The interaction may take place via the console of the computer in the form of instructions. Operating System acknowledges the same, does the corresponding action and informs the operation by a display screen.
- Error-detecting aids — Production of dumps, traces, error messages and other debugging and error-detecting methods.
- Coordination between other software and users – Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.
MS – Window
MS-Windows is a GUI (Graphic User Interface) based operating system. In Windows Operating system multiple applications can be simultaneously run in different windows.
- In MS-Windows, the screen upon which icons, windows, too are displayed is known as Desktop.
- An icon is a graphic symbol that represents a window element like, file, folder, or shortcut.
- Loading up of operating system files into the computer’s memory in called booting up.
- The taskbar is a bar, which is usually located at the bottom of the screen.
- My computer is helpful for viewing the contents of a single folder or drive.
- Windows Explorer is another way of seeing what is on your computer. Windows Explorer shows the computer’s contents as a hierarchy.
- File: A program or document stored on a disk.
- Toolbar: A set of buttons you click to perform common tasks.
- A folder is a location in which you can store files and other folders.
- To create a new folder, File—New—Folder commands are clicked in My Computer windows.
- To find files or folders, Start—Find—Files or Folder commands are clicked.
- To create a shortcut to a file, firstly select the file or folder, whose shortcut is to be created. Then drag the file icon through right mouse button to desired location where shortcut to be placed, and then select create shortcut(s).
- To shut down the computer, Start—Shut Down commands are clicked.
|Ctrl+W||Close the active window / document|
|Ctrl+Z||Undo an action|
|Ctrl+Y||Redo the last action or repeat an action|
|Ctrl+S||Save a document|
|Ctrl+P||Print a document|
|Ctrl+K||Insert a hyperlink.|
|Alt+Right.||Arrow Go forward one page.|
|Ctrl+C||Copy selected text or graphics to the Office Clipboard.|
|Ctrl+V||Paste the most recent addition to the Office Clipboard.|
|Ctrl+Shift+A||Format all letters as capitals.|
|Ctrl+B||Applies or removes bold formatting.|
|Ctrl+I||Applies or removes italic formatting.|
|Ctrl+=||Apply subscript formatting (automatic spacing).|
|F4||Repeat the last action performed(Word 2000+)|
|F5||Open the Find, Replace, and Go To window in Microsoft Word|
|F7||Spellcheck and grammar check selected text or document|
- The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to link several billion devices worldwide. It also known as “network of networks” that consists of millions of private, public, academic, business, and government networks.
Various Applications of Internet are:
- Exchange messages using e-mail (Electronic mail).
- Transfer files as well as software.
- Browse through information on any topic on web.
- Communicate in real time (chat) with others connected to the internet.
- Search databases of government, individuals and organizations.
- Read news available from leading news groups.
- Send or receive animation and picture files from distant places.
- Set up a site with information about your company’s products and services.
The World Wide Web commonly known as the Web or www developed founded by Tim Berners – Lee in 1989, is a system of interlinked hypertext documents that are accessed via the Internet. These multimedia pages are ever- changing.
- A web browser (commonly referred to as a browser) is a software application for retrieving, presenting and traversing information resources on the World Wide Web.
Ex. WorldWideWeb( First Web Browser), Netscape, Internet Explorer, Opera, Mozilla Firefox, Safari, Google Chrome,
Various features of a Web Browser are:
- Menu bar: The menu bar, located at the very top of the screen, can be accessed using the mouse. Actions that are in black can be performed, while actions that cannot be performed will be in gray or lightened.
- Tool bar: The tool bar is located at the top of the browser; it contains navigational buttons for the Web. Basic functions of these buttons include:
|Home||Opens or returns to starting page|
|Back||Takes you to the previous page|
|Forward||Takes you to the next page|
|Prints current page|
|Stop||Stops loading a page|
|Reload||Refresh/redisplays current page|
|Search||Accesses search engine|
- Location bar: The location bar, below the tool bar, is a box labelled “Location,” “GoTo,” or “Address.” You can type in a site’s address, and press the Return or Enter key to open the site.
- Status bar: The status bar is located at the very bottom of the browser window. You can watch the progress of a web page download to determine if the host computer has been contacted and text and images are being downloaded.
- Scroll bar: The scroll bar is the vertical bar located on the right of the browser window. You can scroll up and down a web page by placing the cursor on the slider control and holding down the mouse button.
- A website is a set of related web pages served from a single web domain.
- The Uniform Resource Locator, abbreviated as URL is the Address for web sites. Most of them begin with http (HyperText Transfer Protocol), followed by a colon and two . In most web browsers, the URL of a web page is displayed on top inside an address bar. An example of a typical URL would be “http://www.cbsenetonline.in“.
- A Home page, index page, or main page is a page on a website.
- A Hyperlink is a reference to data that the reader can directly follow either by clicking or by hovering or that is followed automatically.
- Downloading means to receive data to a local system from a remote system, or to initiate such a data transfer.
- Uploading refers to the sending of data from a local system to a remote system such as a server or another client with the intent that the remote system should store a copy of the data being transffered.
ELECTRONIC MAIL (e-mail):
Electronic Mail (e-mail) was invented by “John Von Neumann”. Electronic Mail transfers the data from one system to another system in the form of messages (test), pictures (images), Multimedia messages.
An e-mail address normally consists of Three parts.
- Name of the User
- “@” Sign
- 3rd part comes after @ sign and it is the name of the DNS.
Example : cbsenetonline @ gmail .com
User Name “@” sign Domain Name System (DNS)
To view an e-mail, you have to use e-mail software is “Outlook Express”.
In the e-mail window, you can find “Folder Pane” at the left side of the window. It has set of folders named as Composed email, Inbox, Out Box, Sent Items, Drafts, Trash, Spam etc.,
- Inbox is used to store incoming
- Outbox is used to store outgoing email before it is
- Sent Items is used to store email that has already been
- Deleted Items (Trash) is used to store deleted email up to 30
*. A draft folder is used to store email that is not yet complete.
- Spam is used to store the unsolicited bulk e-mail up to 30
- Compose Mail is use to create a new
- To : To type the e-mail address of the person to whom you want to send an email in this
- Subject : To type a few words about the subject of the letter you want to
- CC (Carbon Copy) : To type the e-mail address of the other recipients in this box, each address is separated by a comma (,). When you complete the mail and click the “Send” button, then the mail will automatically be sent to all the recipients. Here, all the recipients will know who the other recipients
- BCC ( Band Carbon Copy) or (Blind Curtsey Copy) : If you don’t want them to know who else have received copies, you can type the addresses in the BCC text In this case, only you (the sender) will know the identity of all the recipients of mail.
- Reply : You can send your reply using the same The subject box will have the same subject, but with the words “Re:” before it.
- Forward : You can send the forward message using the same The subject box will have the same subject, but with the words “Fwd:” before it.
- An email attachment is a computer file sent along with an email message. One or more files can be attached to any email message, and be sent along with it to the The first email was sent by Ray Tomlinson to himself in 1971.
- The Drafts folder retains copies of messages that you have started but are not yet ready to send.
- Hotmail, a free e-mail service provided by Microsoft which was established in 1995 was co-founded by an Indian American entrepreneur Sabeer Bhatia along with Jack Smith in July of 1996.
- An Internet Protocol address (also known as an IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network. It acts as an identifier for a computer. It is a unique address for every computer.
- Top-level domain: Each part of a domain name contains certain information. The first field is the host name, identifying a single computer or organization. The last field is the top-level domain, describing the type of organization and occasionally country of origin associated with the For e.g. – .com – Commercial, .edu – Educational.
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
- Internet Protocol (IP)
- Post Office Protocol (POP3)
- Hyper Text Transfer Protocol (HTTP)
- File Transfer Protocol (FTP)
- Internet Control Message Protocol (ICMP)
- Internet Message Access Protocol (IMAP)
Function keys – A function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions, a form of soft key. For e.g. – F1 through F12 keys are known as function keys. Each keys perform different functions.
E – Commerce (Electronic Commerce) : E-Commerce is the buying and selling of goods and ser- vices on the internet. The visitor to the site can sell or buy any product or service online. The transac- tions are enable through credit cards, Debit cards etc.
E-Business (Electronic Business) : E-Business is the administration of conducting business via the Internet. This would include the buying and selling of goods and services, along with providing technical or customer support through the Internet. E-Business is used in conjunction with E-Com- merce, but includes services in addition to the sale of goods.
E-Administration: The use of ICTs (Information and Communication technologies) to modernize the state, the creation of data repositories for MIS (Management Information Systems), computerisation of records.
E-Services: the emphasis here is to bring the state closer to the citizens. Examples include provision of online services. E-Services and E-Administration together constitute what is generally termed e-governance.
E-Governance: The use of IT to improve the ability of government to address the needs of society. It includes the publishing of policy and programme related information to transact with citizens. It extends beyond provision of on-line services and use of IT for strategic planning and reaching development goals of the government.
E-Democracy: The use of IT to facilitate the ability of all sections of society to participate in the governance of the state. The remit is much broader here with a stated emphasis on transparency’, accountability and participation. Examples are online disclosure policies, online grievance redress forums, and e-referendums.
Electronic Funds Transfer (EFT): A cashless approach used to pay for goods and services. Electronic signals between computers are used to adjust the accounts of the parties involved in a transaction. Electronic Funds Transfer (EFT) is also known as “Electronic Banking (E-Banking)”. E-Banking is the use of electronic means to transfer funds directly from one account to another, rather than by cheque or cash.
Internet Banking or Online Banking: internet Banking allows customers to conduct financial transactions on a secure website operated by their retail or virtual bank, credit union or building society.
E-Marketing: E-Marketing is also known as Internet Marketing, Digital Marketing, Web Marketing, Online Marketing, Search Marketing, I-Marketing (Internet Marketing) is the Marketing of products or services over the Internet.
E-Procurement (Supplier exchange): E-Procurement is more than just a system for making purchases online. A properly implemented system can connect companies and their business processes directly with suppliers while managing all interactions between them. Examples are bids, management correspondence, questions and answers, previous pricing and multiple emails sent to multiple participants.
Types of E-Commerce:
- Business to Customer (B2C): The basic concept of this model is to sell the product online to the customers. It provides direct selling through online. B2C is the indirect trade between the company and consumers. Directly interact with the customers is the main difference with other business models.
- Business to Business (B2B): It is similar to manufacturer issuing goods to the retailer or whole- This model defines that Buyer and seller are two different entities. It consists of the longest form of E-Commerce. It is one of the cost-effective ways to sell out product throughout the world.
- Customer to Customer (C2C): It helps the online dealing of goods or services among though there is no major parties needed but the parties will not fulfill the transactions without the program which is supplied by the online market dealer such as eBay.
- Peer to Peer (P2P): It is a discipline that deals itself, which assists people to instantly shares related computer files and computer sources without having to interact with central
- M-Commerce: This model deals with conducting the transactions with the help of mobile. The mobile consumers can interact each other and can lead the business. M-Commerce (Mobile Commerce) involves the change of ownership or rights to utilize goods and related services.
Companies and Their Founders :
Microsoft Bill gates
Google Sergey Brain and Larrypase (1997)
Yahoo Journeying and David(1994)
Facebook Mark Zuckerberg
Apple Steve Jobs
Oracle Tim Nerveski
Wikipedia Jimmy Wales
Twitter Bizz Stone
Security: Security controls access to data in files and permits only authorized use of terminals and other equipment. Control is usually through various levels of passwords assigned on the basis of need to know.
Typical approaches to improving Computer security can include the following :
- Physically limit access to computers to only those who will not compromise security.
- Hardware Mechanisms that impose rules on computer programs, thus avoiding depending on computer programs for computer security.
- Operating system Mechanisms that impose rules on programs to avoid trusting Computer Programs.
- Programming strategies to make computer programs dependable and resist superversion.
Firewall: A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users of other networks. Firewall can either be hardware devices or software programs. They provide protection from Online intrusions. A firewall is designed to pre- vent unauthorized Internet users from accessing your computer. All messages entering your Computer from the Internet pass through the firewall which examines each message. The firewall blocks any message that was not specifically requested by your system.
Encryption: It can be used to protect the message from unauthorized users. It can be done in several ways by switching the characters around, replacing characters with others, and even removing characters from the message.
Cryptographic Techniques: It can be used to defend data in transit between systems reducing the probability that data exchanged between systems can be intercepted or modified. Secure crypto processors can be used to leverage physical security techniques into detecting the security of the system. Strong authentication techniques can be used to ensure that communication end-points are who they say they are.
Intrusion – Detection – System: It can be scan a network for people that are on the network but who should not be there or redoing things that they should not be doing. For example trying a lot of passwords to gain access to the network.
Pinging: The Ping application can be used by potential crackers to find if an IP address is reachable. If a cracker finds a computer they can try a port scan to detect and attack services on that computer.
Anti-Virus Software : Anti-virus software consists of computer programs that attempt to identify, thwart and eliminate computer viruses and other malicious software (Malware). The term “Antivirus” is used because it is designed exclusively to combat computer viruses.
Antivirus software typically uses two different approaches to accomplish this:
☛ Examining (Scanning) files to look for known viruses matching definitions in a virus dictionary.
☛ Identifying suspicious behaviour from any computer program which might indicate infections.
VIRUS (Vital Information Resource Under Siege): The full form is “Vital Information Resource Under Siege”. A computer virus is a computer program that spreads by inserting copies of itself into other executable code or documents. Virus program that runs on your computer without your knowledge and can cause damage to your files. A common way to receive a virus is through an attachment via e-mail.
Worm: Worm is a self-replicating program. It replicates itself to new computers using the flaws and then begins scanning and replicating again. The difference between a virus and worm is that a worm does not create copies of itself on one system. It propagates through computer networks.
Trojan Horse: It is a program in which malicious or harmful code is contained inside apparently harmless programming or data in such a way that it can get control and do its chosen form of damage. Trojan Horses cannot replicate automatically. A Trojan horse can be used to setup a backdoor in a computer system so that the intruder can return later and gain access.
Malware (Malicious Software) : It is a software designed specifically to damage or disrupt a system such as a virus or Trojan horse.
Spyware: Spyware is a software that performs actions such as advertising, collecting personal data, or changing the configuration of your computer, usually without obtaining your consent. Spyware that displays advertisements and tracks your personal information is known as “Adware”.
Spam: E-mail spam also known as “Junk e-mail” or “Unsolicited Bulk e-mail (UBE), is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail.
Phishing: Phishing is a fraudulent activity of acquiring the sensitive information by the use of a fake identity during electronic communication.
Spoofing: It occurs when the sender of an e-mail message pretends to be someone else, they falsely manipulate the “From” field in an e-mail. This is usually done to make you release sensitive information.
Key loggers : Key logger is a software program designed to record (log) every keystroke on the machine on which it runs. Key logger is also known as “Key Stroke logger” or “System Monitor”.
Packet Sniffer: A packet sniffer is an application that captures TCP/IP data packets, which can maliciously be used to capture passwords and other data while it is in transit either within the computer or over the network.
Root Kit: A root kit is a computer program that enable administrator – level access to a computer or computer network. A cracker installs a root kit on a computer after first obtaining user-level access, either by exploiting a known vulnerability or cracking a password. Once the root kit is installed, it allows the hacker to mask intrusion and gain root or privileged access to the computer.
Cyber crime: It contains all criminal offenses which are committed with the aid of communication devices in a network.
- Unauthorized access, malicious code, and denial-of-service
- Theft of service and certain financial
- Spamming and copyright crimes, particularly those facilitated through peer-to-peer
- Hacking, phishing, identify theft, child pornography, online gambling securities
Hacking: Hacking is the activity of programmatically gaining access to a computer application that is otherwise inaccessible. The act of gaining an unauthorised access to a computer is known as “Hacking”.
Hacker: A Hacker is someone involved in computer security specializing in the discovery of exploits in systems in obtaining or preventing unauthorized access to systems through skills, tactics and detailed knowledge.
Polymorphic Virus: A polymorphic virus modifies its program code each time it attaches itself to another program or file.
Commonly Used Computer Terms
• Abort: To stop a program or function before it has finished.
• Algorithm: A set of instructions that provides a solution to a given problem.
• Animation: A simulation of movement created by displaying a series of pictures, or frames. For example, cartoons on television.
• ANSI: American National Standards Institute, a powerful industry association of USA, promoting Programming language standards.
• Antivirus: Program A utility that searches a hard disk for viruses and removes any, that is found.
• Architecture: A design. It can refer to either hardware or software or to a combination of hardware and software. The architecture of a system defines its broad outlines.
• ASCII: American Standard Code for Information Inter change. This is a seven/eight bit code widely used in computers for the transfer of data.
• Bandwidth: The amount of data that can be transmitted in a fixed amount of time. It is usually expressed in bits per second (bps) or bytes per second.
• Bit: The smallest unit of information in computer system. Bit is short for binary digit; either a “1” or a “0”.
• Boot: The process of getting the computer started.
• Byte: A byte is made up of 8 bits. The amount of memory it takes to store a single character.
• Cache: A separate area of Primary Memory (RAM) where the computer stores a copy of frequently used information for quick access. This is meant to speed up the operation of the hard disk.
• CD-ROM: Compact Disk-Read Only Memory. This is a permanent storage device used to store large quantities of information that need not be changed.
• CGA: Color Graphics Adapter. Low-resolution screen (640×200 pixels) with color capability.
• Character: A number, letter, symbol, or punctuation mark.
• Chip: A small piece of silicon containing thousands or millions of electrical elements. Also called an Integrated Circuit (IC).
• Compatible: The ability of one device or program to work with another device or program. For example, a printer and a computer are said to be compatible if they can be connected to each other.
• Conventional Memory: The first 640K of electronic Memory (RAM) in a computer used to run OS and applications.
• Debug: In computer related systems, fixing software related problem is known as debugging.
• Digitize To scan a piece of artwork in very fine detail and store it in a form that computer understands.
• DOS: It stands for Disk Operating System. It is a single user operating system.
• DVD: Digital Versatile Disc or Digital Video Disc
• Dynamic: Refers to actions that take place at the moment they are needed rather than in advance.
• EDP: Electronic Data Processing.
• E-Mail: Electronic Mail. A facility to send electronic messages to another person on a computer network.
• End-User: The end user is the individual who uses the product after it has been fully developed and marketed.
• EPROM: Erasable Programmable Read Only Memory. A type of ROM that can be programmed or reprogrammed usually by exposing a normally covered sector to UV-Light.
• Extended Memory: Memory in addition to conventional memory used to run and manage applications; together with expanded memory, it helps PCs to address increased amounts of data in memory.
• Fax/Facsimile: A way of transmitting copies of documents over telephone lines. Fax is short for Facsimile.
• Gigabyte: Abbreviated as GB, is equal to 1024 MB. GUI Graphical User Interface. A user interface that works visually and is based on the selection of actions using a mouse or a similar pointing device to click on icons or to pick options from menus; see also icon.
• Hertz: A unit of frequency that means Cycles per Second.
• High Density: The amount of information a disk can hold. High Density disks hold more information than Double Density disks.
• Hypertext: A method of presenting information so the user can view it in a non-sequential way, regardless of how the topics were originally arranged. It has now evolved as a flexible software technology to create electronic books provides fast and flexible access to search criteria and provides quick access to information in large documents.
• HTML: Hyper Text Markup Language. A markup or structuring language used to describe Web and Intranet documents. It is used to define structure, appearance and placement of HTML elements including, fonts, graphics, text, hypertext links to other sites and many more details.
• IBM: International Business Machines, a USA based multinational Company.
• Icon: A graphical screen element that executes one or more commands when selected with a mouse or other pointing device
• IDE: Integrated Device Electronics, a standard used for connecting hard drive to a computer. IDE hard drives are very common and relatively inexpensive.
• Intel: The manufacturer of the most popular microprocessors or CPUs.
• Intelligent: Printer Printer combining laser, computer and photocopying technology.
• Internet: The world’s largest computer network that links many of the scientific, research and educational computers as well as commercial networks. The internet uses TCP/IP protocols, and computers on Internet can run on any operating system, like, several variations of UNIX, Windows NT, and VMS etc.
• Intranet: In the most general sense, a private corporate network that uses Internet technology based software and TCP/IP protocol standards. Many companies use intranets for tasks as simple as distributing a company letter and for tasks as complex as posting and updating technical support bulletins to service personnel worldwide. An intranet does not always include permanent connection to Internet.
• Kilobyte (K, KB) Approximately one thousand characters; actually 1024bytes.
• LAN An acronym for local area network. A system of PCs that are located relatively near to each other and connected by wire so that individual users can cooperatively process information and share resources; see also WAN.
• Laptop Computer: A portable computer, small enough to be held on a lap,but slightly larger than a notebook computer.
• LED: Light Emitting Diode. An electronic device that lights up when electricity is passed through it.
• Light Pen: An input device that allows a user to write on or point to a special pad or the screen of a pen- based computer, such as a PDA.
• Macintosh: A PC based on a Motorola microprocessor employing GUI. Apple Macintosh has been in use since late eighties.
• Macro: A symbol, name, or key that represents a list of commands, actions or keystrokes.
• Math co-processor: Part of the microprocessor; a companion chip designed to perform complex calculations.
• Megabyte (M, MB): Approximately one million characters; actually 1,048,576 bytes. A measure of memory or storage.
• Megahertz (MHz): A measure of processing speed. The higher the value, the faster a computer can work.
• Microprocessor: A single chip containing all the elements of a computer’s CPU.
• MIPS: Million Instructions Per Seconds, a unit for measuring the speed of a computer.
• Mother Board: The main circuit board of a computer, which carries electrical signals to and from various parts of the computer.
• Multimedia: A computer system that combines text, graphics, animation, music, voice and video media; may include stereo speakers as an output device.
• Multiprocessing: It refers to a computer system’s ability to support more than one process at the same time. It is also called multitasking.
• Nibble: Half a byte i.e. 4bits.
• Non-Volatile Memory: This is data storage that does not lose its contents on power off; for example, ROM.
• Notebook Computer: A portable computer, approximately 8½ by 11 inches, that fits inside a briefcase.
• Numeric keypad: The part of a keyboard that looks like an adding machine, with 10 digits and mathematical operators; usually located on the right side of the keyboard.
• Office-Automation: The use of computer systems to execute a variety of office operations, such as word processing, accounting and Email.
• Parallel Port: An outlet on a computer used to attach a device, such as a printer. A parallel port sends data (bits) down the wire side by side (parallel to each other).
• Pentium: The fifth generation of microprocessors. The Pentium is 2 to 3 times faster than the 80486, the fourth generation of microprocessors.
• Peripheral: Any piece of hardware attached to the outside of a computer. Examples are printers and modems.
• Pixel: Short for “Picture Element”. A Pixel is the smallest dot the computer can control on the screen.
• Portable computer: A small computer that usually runs on batteries. In the categories of portable computers are laptop, notebook, sub-notebook and palmtop.
• Protocol: In networking and communications, the formal specification that defines the procedures to follow when transmitting and receiving data. Protocol defines the format, timing, sequence and error checking used on the network.
• Resolution: The size and quantity of dots that make up a printed page, screen or scanned image.
• Runtime: Error An error that occurs during the execution of a program.
• Scanner: An input device used to copy a printed document into a computer’s memory in digital form, without requiring manual keying.
• SCSI: Small Computer System Interface. A standard for connecting a hard drive to a computer.
• Serial Port: An outlet on a computer used to attach a device, such as a modem. A serial port sends data (bits) down the wire one at a time (in a series).
• Service Pack: It is an update to a software version that fixes an existing problem, such as a bug or provides enhancements to the product that will appear in the next version of the product.
• TCP/IP: Transmission Control Protocol / Internet Protocol is a set of communication protocols that encompass media access, packet transport, session communications, file transfer, e-mail, and terminal emulation. TCP/IP is supported by a large number of H/W and S/W vendors and is available on many computer systems, from PCs to mainframes.
• Troubleshoot: To isolate the source of a problem and fix it. In case of computer systems, troubleshoot is usually used when the problem is hardware related.
• UNIX: A multi user operating system.
• Upgrade: A new version of a software or hardware product designed to replace an older version of the same product.
• UPS: Uninterruptible Power Supply. It is a power supply that includes a battery to maintain power in the event of a power cut for several minutes to some hours.
• Utility: A program that performs a very specific task, usually related to managing system resources.
Disclaimer – The study materials are provided from the personal notes of a JRF Qualified. Need suggestions for any publishing or conceptual mistakes. Feel free to comments with your suggestions or clarifications.