The computer as we know it today had its beginning with a 19th century English mathematics professor name Charles Babbage. He designed the Analytical Engine and it was this design that the basic framework of the computers of today are based on. Below are the detail History of Computers.

History of Computers: There are five generations of computer till today. In the early 1820s “Charles Babbage” designed a computing machine called the Difference Engine. It is used in calculating the simple math tables. In the 1830s he designed a second computing machine called the Analytical Engine. This machine is used in calculating complicated problems by following a set of instructions.
Generations of computer:
Types Of Computers: On the basis of its functionality, size, speed and cost computers can be divided into three types.

1. Analog
2. Digital
3. Hybrid

1. Analog Computers A computer in which numerical data is represented by the measurable physical variable which varies continuously, such as speedometer, electrical voltage, pressure, temperature etc. Analog computers were used in olden days to measure the voltage of current, in weighing machines and in some scientific industries.
2. Digital Computers A computer that performs calculations and logical operations in which data is represented in digital form, usually binary 0’s and 1’s, ternary or in other numeral systems. Digital computers were used widely in digital speedometers in mechanical industries, digital signal processing etc.
3. Hybrid computers The combination of analog and digital computer systems is called hybrid computers. It accepts both analog and digital as input and it converts digital to analog and analog to digital information. Hybrid computers were used in hospital (in ICU), petrol pumps and in some industrial units.
Classes of computers: Based on types and sizes of computers are divided into classes. We know in olden days computers were occupying large space (vacuums tube) but in nowadays it is very small in size (laptops).So based on this computers are divided into four classes
1. Microcomputers (personal computers) Microcomputer, an electronic device with a microprocessor as its central processing unit (CPU). A microcomputer is also known as personal computers. It performs all logic and arithmetic operations. It contains a single chip on which all CPU, memory, interface circuits, and input&output devices are connected.
Examples are Personal Computers, Laptops, Tablet PC, Note Pad, Smart Phones etc.
2. Minicomputers (midrange computers) A Minicomputer is a type of computer that has more processing power than personal computers but less powerful than mainframe computers. Minicomputers are mainly used as small or mid-range servers operating business and scientific applications.
Minicomputers are used for complex computations in the fields of science and engineering, used as communication tools in larger systems and data management.
3. Mainframe computers A very large and expensive computer which can maintain hundreds or even thousands of users simultaneously. Mainframes computers are more powerful than supercomputers because it executes multiple programs at the same time but at the same time supercomputers can execute single program faster than mainframe computers.
Mainframe computers are used in ATM machines and also used by large corporations and government agencies to store a large amount of data.