Science has revolutionized the life of modern man. Scientific inventions and discoveries have reduced human sufferings and given him relief from hardships of manual works. Computer is one of the most wonderful and latest invention of the modern science. It is so popular that people call it an electric wonder. . All the nations of the world are in the grip of this technology.

Computer was invented for computing fast. It is an electronic device that can recieve set of instruction or programs and then carry out these programes by performing calculation on numerical data. The modern technology is possible only because of computer . It is source of creation .

It has become essential in schools and colleges. Thousands of videos games or videos of any thing else can be played on it. There are nearly 7 billion websites in the world.  With the help of computer it i possible to connect the people with each other in unbelieveable cheap rates .Data base services and computer networks give  a great variety of information sources which makes the vision of personal and business privacy. It has become a treasure of knowledge. Very large books have been transferred on cds. And if cd is inserted in cd rom, so any kind of information can be achieved. It is used in post offices, banks  and travel agencies like railways airlines and hotels.

Online banking and jobs is now possible with the help of computer. Money can be sent to any where in  seconds. Account data information can be stored in computer. Online shopping is also possible with the help of computer . FBI has stored information about  every American  in order to trace the criminals . Different kinds of softwares are  made for making work easy.

It is very useful device and is also used by doctors for diagnosing area of operation. Modern digital computers have made the screen digital. The computer is divided in to several catagories on the basis of cost of perfomances. Personal computer or microcomputer is of low cost. It is in the size of desktop. It has graphics and communication capabilities that make it especially suited to business, school laboratories. Mainframe computer is a large expensive machine. It has the capability of serving needs of major business enterprises, governoment departments and scientific researches.

The large and fast computer among these is called super computer. Digital computer is not a single machine it is composed of  five distinct elements. A central processing unit or (cpu) is an input device which stores memory stor . A communication network called bus which  links all the elements of the system  . In short may be a  time will come that computer will take place of man, and the world will be called the world of computer.