An electronic device that takes data as input from users, processes it, and provides output. It performs arithmetic and logical operations according to programming instructions. Common components include a central processing unit, memory, storage devices, input devices like keyboards and mice, and output devices like monitors and printers. Computers are used for tasks like data processing, scientific research, and more. They have advantages over humans like speed, accuracy, and storage capacity.

1. What is computer?
An electronic device that is given instructions to perform arithmetic or logical operations
via computer programming.
Definition of device
An equipment used for particular purpose which runs either electronically or
mechanically.
Definition of instructions
It is a detailed information about how something is done or operated.
Arithmetic
A branch of mathematics that deals with numbers and their operations with addition,
subtraction, multiplication and division.
Logical
According to the rules and logic and based on facts and ideas.
Operation
An act performed by a machine or computer is called operation.
Programming
The process of writing and testing programs for computers.
Definitions of computer
It is an electronic equipment which is given detailed information to perform numerical
operations with addition, subtraction, multiplication and division and works according to
logical rules based on facts and ideas via computer processes of writing and testing
programs.
An electronic device that takes data from the user as input and gives data to the user as
output after processing it.
It is a machine that carries out a series of operations on data less than a second and gives
results according to instructions that are given to it.
Advantages of computer:
1. The computers have more capability of getting high productivity with less wasted effort
as compared to humans.
2. Work done by computers is better in quality and performance as compared to human
work.
3. Computers offer an advantage of accumulating of large amount of data in one place.
4. Computers are efficient in doing several hard tasks with a very short time and now the
processing speed of new computers is increasing day by day as compared to old
computers.

2. Definition of term:
A meaningful word that refers to objects, ideas, events or state of affairs is called term.
Definition of Input
The information that goes into the computer is known as input. Examples include typing
letters and scanning images etc.
Definition of peripheral
A device that can be attached and used with a computer is called peripheral.
Input devices
Those peripherals which are used to give data and orders to computer are called input
devices. Examples include scanner and keyboard etc.
Definition of Output
The amount of data produced by computer in meaningful form as a result, is called
output. Examples include sound via speaker and printed page by a printer.
Definition of output devices
The physical components of computer used for getting results of data in the form of
meaningful information are called input devices.
Definition of Processing
The process of performing a series of operations on data in order to convert it into
meaningful information according to given instructions is called processing.
Definition of storage
It is the capacity of computer to accumulate data or information according to given
orders.
Definition of storage devices
The devices which are used to store data are called storage devices. Examples include
hard disk, floppy disk and CD-ROM.
Definition of Hardware
Tangible parts or components of computer are called hardware. Examples are CPU,
monitor, keyboard and speaker etc.
Characteristics of hardware
1. Hardware can be touched and felt.
2. Hardware decides what software will be used in computer.
3. Computer hardware is not cheap and easy to access.
Definition of Software
A set of computer programs that provides guidance to the computer during the data
processing is called software. In other words, software helps computer in operating.
Characteristics of software
1. It is intangible (cannot be touched)
2. It is weightless.
3. It is used to operate the computer.

3. Types of computers
There are five basic types of computer.
1. Super computers
2. Mainframe computers
3. Minicomputers
4. Personal computers
5. Portable computers
Super computer
These computers are the fastest in speed and due to their speed and vast storage, they have the
capability of doing complex operations such as weather fore-casting and scientific research.
These computers use hundreds of thousands of processors.
1. Advantages of super computers
2. High speed
3. Most appropriate in accuracy
4. Examples include Belle, Deep blue and Hydra computers.
Mainframe computers
Through these computers, all the processing is carried out centrally. These computers are used by
large organizations for bulk data processing such as census.
Minicomputers
These computers are less in speed than super computers and can support 200 hundred
users at the same time and are larger in size than desktop computers.
Personal Computer
Personal computer is abbreviated as PC and it is cheaper than super, mainframe and
minicomputers.
Portable computers
These are small personal computers and can be carried from one place to other. A
portable computer is combined with all of the typical components of a desktop computer.
Keyboard
It is an input device for giving data or information to the computer and is called keyboard
because keys are attached with board.
Keyboard types
There are several types of keyboard, among these, standard keyboard is used most
commonly. Besides this, keys’ arrangement is different for different keyboards. In
addition to that, some keyboards have special keys for special tasks such as video editing
and sound designing etc.
Basic keyboard keys
On standard keyboard, there are 104 keys generally.
Key stroke
Pressing the key one time and releasing it, is called a key stroke.

4. Character keys
These keys are used to enter alphabetic letters and to make them in upper case
either pressing with shift key or making caps lock on.
Numeric keys
Numeral keys are used to enter numbers in computer and these keys become
symbols or punctuation marks when pressed with shift key.
Special keys
Shift, Alt and control (ctrl) keys are special keys and pressed with other keys to
perform special operations. For example to select a file or text, press ctrl+A and to
paste it press ctrl+V
Escape key
Pressing this key, cancels the current operation or exits current window.
Function keys
Function keys are labelled as F1 to F12 keys and are used for different purposes.
For example F5 is used to refresh the web page in internet browser.
Arrow keys
These keys are four in number and their function is to navigate the cursor.
Numeric keypad
Numeric keypad is an isolated set of keys on right side of some keyboards that
contains the numbers from 0 to 9 and mathematical operation keys which are used
for calculation purpose. It also contains an enter, a dot or numeric lock key.
Space bar key
This key is located on the lower most row of keyboard and is the widest of all the
keys in size. The function of this key is to make space between letters, words or
numbers etc.
Punctuation keys
These keys are located on the right side of alphabet keys and their function is to
punctuate.
Enter key
This key is used to move cursor to the next line or to perform an action. This key
is also called return key.
Menu key
This key is used as right mouse button and launches the menu with the keyboard.
Toggle keys
These keys are three in number and are caps lock, Num lock and scroll lock.
There are three small lights to show the status of these locks on the top right
corner. Alphabetic letters become capital when caps lock is on. When num lock
key is on, it acts as numbers and a dot and when it is off, the keys work as arrow
keys, home key, page up, page down, insert, delete and end keys. When scroll key
is turned on, it moves window instead of moving cursor.
Window
An isolated area of viewing on a computer display screen is called window.

5. Print Screen key
The key used to take the screen shot of the window display screen.
Insert key
The key used to overwrite characters within a word or replace the letters of words.
Home key
It is used to return cursor to the beginning of the line on the user currently types.
End key
It is used to return the cursor to the end of the line on the user currently types.
Page up key
It is used to go to the previous page.
Page down key
It is used to go to the next page
Delete key
This key is used to delete characters.
Backspace key
This key is used to delete the characters that come before.
Tap stop
The location at which the cursor stops after the tab key is pressed is called tab
stop.
Tab key
The key which is used to move the cursor to the next tab stop is called tab key.
Pointing devices
Those devices via which we can control the movement of the pointer on computer
screen are called pointing devices. Examples include mouse, trackball and
joystick etc.
Mouse
A handheld device used to move cursor on a computer screen is called mouse. In
market, mice are different in shapes but they work in same manner.
Mouse button
An electric switch on computer mouse that is used to select or communicate with
an element of graphical user interface, is called mouse button. A standard mouse
has two buttons namely:
1. Right mouse button
2. Left mouse button
Mouse pad
A piece of hard or slightly elastic object on which a computer mouse is moved.
Mouse cursor
A mouse cursor, pointer or mouse arrow is a graphical image that is used to
switch on or control certain elements in graphical user interface.

6. Trackpad
An input device on laptops and some keyboards which allow user to move
cursor with his/her finger is called trackpad.
Trackball
An input device that consists of a ball held by socket and sensors to
identify the rotation of the ball is called trackball. This is used by
computer user to move the cursor in desired direction.
Microphone
An input device used to input the sound to computer, is called
microphone.
Scanner
An input device that scans images or papers etc to store them for editing
and display in computer is called scanner.
Digital camera
A camera that produces digital pictures that can be accumulated in
computer and shown on screen.
Webcam
A digital camera that gives images and receives videos via internet is
called webcam.