As we all know, the computer is a marvelous machine. It has all kinds of types. Nowadays most computers have a memory processor in which information can be stored and be taken out at any time.
The oldest kind of computer is the abacus. It was used in China long agoi The first modern computer was very large and expensive, but now scientists already have been making computers smaller and cheaper, at the same time easier to use and work faster and faster now. At present，the people  usually used OS are windows XP, Vista and win7.
Computers can be used a great deal in many ways. It can do many kinds of work. They can be used in doing business and science research work, in some large factories, and our daily life. We even use it to play computer games at home. Today a lot of people buy computers. Computers is becoming more and more popular indeed. The more and more people approves the notebook computer and the netbook computer.