Today computers have become part of our life. The word “computer” comes from the word “compute”, which means, “to calculate”. Usage of computers in different fields has become a necessity in the present competitive word. Although the original objective of inventing a Computer was to create a first calculating device, we now define a computer as a device that operates upon data because more than 80% of work done by today’s computers is data processing. Lot of work and evolutions has transpired form the initial computer systems to the present day. Computers are made up of Electrical, Electronic and Mechanical Components. Computer is just the machines and you must specify the work that is to be carried out by the computer. A computer is often referred to as a “DATA PROCESSOR” because it can store, process, and retrieve data whenever desired. The activity of processing data using a computer is called “DATA PROCESSING”. Data processing consists of three sub activities: capturing input data, manipulating the data, and managing output results. Hence, data is a row material used as input to data processing and information is processed data obtained as output of data processing (Shown in below).