A computer is derived from the Latin word ‘Computare’ which means ‘calculate’.

So according to this definition, a computer is a machine which can perform calculations at very high speed.

A computer is an electromechanical device that works on command and performs mathematical and logical operations within a short time and with high accuracy.

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem.

The following are the part of the computer.

**CPU (Central Processing Unit)** – Processing unit or CPU which give desired output after processing of input.

**VDU ( Visual Display Unit)** – Display unit is known as monitor it is the output unit. It gives a soft-copy output which we can not touch.

**MOUSE** – Used to give input to the computer. It is an input device which has a pointer to do the movement.

**KEYBOARD** – Keyboard is also input device we have to press keys to give instructions to the computer.

**PRINTER AND SCANNER** – Printer is output device which gives a hard-copy output which we can touch. A scanner is input devices through scanner we can give instruction to the computer.

## Characteristics of Computer

A computer is a powerful machine. It can perform a large number of tasks. The main capacities of the computer are work length, speed accuracy, diligence, versatility memory and automation and lots of more tasks.

**Speed**

The time taken to perform any task by a computer is called the speed of computer as you know a computer can work very fast. It takes only a few seconds for calculations that we take hours to complete. The speed of the computer is measured in MIPS (Millions Inch per Seconds)

**Accuracy**

A computer is an accurate machine. It can perform a large number of takes without errors but if we feed wrong data to the computer it returns the same wrong output or wrong information. If the computer hardware parts are able to work and given input is correct the computer can give 100% accurate result. The process of giving correct result and wrong result is called GIGO (Garbage In Garbage Out).

**Diligence**

The capacity of performing a repetitive task without getting tired is called diligence capacity of the computer. A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error.

**Versatility**

The capacity for performing more than one work is called the versatility of a computer. It means the capacity to perform the completely different type of work. You may use your computer to prepare payroll slips, office work, mathematical calculation, word processing etc.

**Storage**

The computer has a mass storage section where we can store a large volume of data for future work. Such data are easily accessible when needed. Magnetic disk, magnetic tape, and optical disk are used as the mass storage devices. The storage capacity is measured in terms of KB, MB, GB, TB, PB, EB etc…

**Automatic**

Once we give the appropriate instruction, a computer can perform the operations automatically. Like computer can do addition, subtraction, division and multiplication etc. Computer can automatically compare values also. It also does copying the value from one memory location to other locations.

**Power of Remembering**

Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data.

**Word Length**

A digital computer operates on binary digits-0 and 1. It manipulate data only in terms of 0 and 1. A binary digit is called a bit. The number of bits that computer can process at a time in parallel is called its word length. Word lengths computer are varies such as 8, 16, 32, 64 bits. It is the measurement of the computing power of computer.

**Processing**

Computer can process a large volume of data in great speed. There are different types of operation during processing such as input / output operation logic operation comparison operation text manipulation operation.