Introduction

The word computer comes form the word compute, which means, To calculate. Hence, people usually consider a computer to be a calculating device that can perform arithmetic operations at high speed.
In fact, the original objective for inventing a computer was to create a fast calculating machine. However, more than 80% of work done by computers today is of non-mathematical or non-numerical nature. Hence, to define a computer merely as a calculating device is to ignore over 80% of its functions.
More accurately, we can define a computer as a device that operates upon data, data can be anything like bio-data of applicants when computer is used for listing candidates for recruiting: marks obtained by student in various subjects when used for preparing results: details (name, age, sex, etc.) of passengers when used for making airline or railway reservation; or number of different parameters when used form solving scientific research problems, etc.
Hence, data comes in various shapes and sizes depending upon the type of computer application. A computer can store, process,, and retrieve data as and when desired. The fact that computers process data is so fundamental that many people have started calling is a data processor.
The name data processor is more inclusive because modern computers not only compute in the same usual sense but also perform other functions with data that flows to and form them, for example, data processors may gather data form various incoming sources, merge (proceeds of mixing or putting together) the mall sort (process of arranging in some sequence – ascending) them in the desired order, and finally print them in desired format. Notice that none of these operations involves arithmetic computations in the usual sense but a computer is the most suitable device for performing them.
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. As used in data processing, information is data arranged in an order and form that is useful to people receiving it. Hence, data is raw materials used al input to data processing and information is processed data obtained as output of data processing.