An electronic machine, which is intelligent enough to calculate, remember and process statistics and store all your data only to keep it secure, is the computer. Going by definition, A personal computer (PC) is an assembled machine whose original sales price, size, and capabilities make it useful for individuals. It may be a home computer, or may be found in an office often connected to a local area network.

Electronic computers were introduced in 1970's and since then have been of tremendous use. They have grown in size and operation and are classified under four different generations. The first Generation or basic computers, second generation or little improved ones, third generation computers, which came in late 1980s, where microchips were introduced and then fourth generation computers, an era when mankind got much faster with intelligent super computers.

Today, or PC's basically work on operating systems. Often we see Microsoft Windows, Macintosh or Linux as the popular ones. Software applications for personal computers include word processing, spreadsheet, games, and a myriad of personal productivity and special-purpose software. Perhaps the greatest feature a desktop computer has is the fact that quite often it can be upgraded and personalized to suit the user's needs.

Modern personal computers often have high-speed or dial-up connections to the Internet, allowing access to the World Wide Web. In the last four decades we have come a long way and are now confronting supercomputers. Supercomputers are used for high calculation-intensive tasks such as problems involving quantum mechanical physics, weather forecasting climate research, molecular modeling, physical simulations, simulation of the detonation of nuclear weapons etc. Major universities, military agencies and scientific research laboratories are heavy users. Some of the big companies producing supercomputers are IBM, Hitachi and Intel.

Well, computers are definitely the order of the day. Every office and home is having one. Most manufacturers offer several lines at different prices. Budget computers are suitable for routine work, such as e-mail, word processing, and Web surfing. At the first glance, virtually, any computer you buy seem laden with useful software for virus scanning, managing finances, and working with audio or image files. But one should always check before buying that the selected model includes antivirus and anti spyware software that will work for at least one year.