**Introduction:**

Computer is the great invention of the 20^{th} century of last two decades. Computer is an electronic machine that takes data from the user and after processing it convert into useful information. Computer is great invention of 20^{th} century but its origin is about 2500 years old abacus , a simple calculator that was made with beads and wires. That abacus is still used in some country today.

**Beginning** :

Now a day, there are a lot of different between abacus and modern computer but it works on same principle as abacus work i.e. calculation. It work more quickly than human brain. With the invention of abacus , 18 years later a French scientist and philosopher Blasé Pascal invented the first practical mechanical calculator on 1642 named pascaline. In this machine there are a lot of interlocking cogs that are connected in series and perform addition and subtraction of decimal number. And after long decades in 1671 , the German mathematician and philosopher Gottfried Wilhelm Leibniz came up and invented a new machine look like Pascal machine with some advanced features. It can add , subtract and with this it could also multiple , divide and also take square roots of the numbers. One of the pioneering feature in Gottfried machine is that for the first time memory store or “register” introduced in it. With the invention of first mechanical calculator , Leibniz remembered to the contribution of one more important in computing. He was the man who invented binary code that works on one and zero code. The binary code or binary language is the language of the computer. A computer can only understand zero and one language. Any decimal digit or any character that we enter through keyboard computer first convert it into binary code that the language of the computer then execute the that instruction and give a useful information that we want. Leibniz did not use binary concept in his calculator. He gave the idea of binary language. After the death of Leibniz , Englishman George Boole used this idea and invented a new mathematics branch named Boolean algebra. Now a day , computer used both binary language and Boolean algebra for making decision of long string of zeros and ones. The abacus by Pascal and mechanical calculator by Leibniz are not qualified for computer. In calculator a human operator is need to perform sums but in computer it needs no human to perform the calculation. It is a machine that perform calculation automatically without human operator by following or perform series of instructions one by one that stored. This stored instructions is called program. Calculator convert into computer when people devised ways to perform all tasks automatic. The first person who made the first simple computer was named Charles Babbage. He was called the father the of computer. In his computer it takes inputs , have memory , processor and outputs all basic components that a modern computer have.

**Advancement:**

Later as the technology changes the computer technology is also change. Now very fast and powerful computer invented that do any calculation in nano seconds. ** **

**For More Info Go To Link Given Below:**

https://en.wikipedia.org/wiki/History_of_computer_science