A computer is an electronic machine that takes input from a user, processes the given input and generates output in the form of useful information.
A computer accepts inputs in many forms such as data, programs and user reply.

DATA -> raw details that require processing for generating useful information
PROGRAM -> set of instructions that can be executed by computer in sequential or non-sequential order
USER REPLY -> input provided by the user in response to query asked by computer


1. Speed
A computer can do any tasks in fractions of a second. The speed of the computer is based on its hardware configuration.

2. Storage Capacity
A computer can store a huge amount of data in many different formats.

3. Accuracy
A computer carries out any calculation with a 100% accuracy. However, this depends on the configuration of the system and instruction from the user.

4. Reliability
A computer process results with 0 error. Mostly the error generated in the computer is due to the user’s fault.

5. Diligence
A computer can be set to perform repetitive tasks for numerous times and the result will always be displayed with the same accuracy and efficiency. Computers aren’t affected by human traits like dizziness, fatigue, distraction, tiredness, etc.

6. Versatility
The same computer can be used for many different tasks for many different purposes.


1. Mechanical Era
2. First Generation Computer
Employed: 1940 – 1956
Technology used: Vacuum Tube
Tasks done: Mathematical Calculation

Advantages: fast computing in their time, executed complex mathematical problems in an efficient manner
Disadvantages: Operated on machine language (0s and 1s), not flexible for running different applications, large and bulky in size and consumed high power

3. Second Generation Computer
Employed: 1956 – 1963
Technology Used: Transistors
Improvements: development of printer, secondary storage, operating system technology, replacement of machine language with assembly language
Tasks done: Mathematical Calculation

Advantages: fast computing in their time, easy to program (assembly language), smaller in size and consumed less power
Disadvantages: I/O devices not improved to a considerable extent, generated a huge amount of heat, beyond the access of households

4. Third Generation Computer
Employed: 1964 – 1975
Technology Used: Integrated Circuits (I.C.)
Improvements: I.C.s made the size of computer smaller, performance efficient and faster and reliable

Advantages: computational time reduced to nano-seconds, use of high-level language
Disadvantages: low storage, costly

5. Fourth Generation Computer
Employed: 1975 – 1989
Technology Used: LSI, VLSI
Improvements: GUI, new Operating System, development of LAN

Advantages: Size and cost minimized, accessible by home users
Disadvantages: complex microprocessor design and fabrication,

6. Fifth Generation Computer
Employed: 1989 onwards
Technology used: ULSI
Improvements: portable computers – laptop, pocket computer, PDA, etc. developed, developed parallel processing, invention of optical disk technology, Internet invented

Advantages: True AI, advanced parallel processing, portability, superconductor technology
Disadvantages: sophisticated and complex tools