What is a Computer?

A computer is a programmable machine that allows users to store and process information quickly and automatically. A computer allows the user to store all sorts of information and then ‘process’ that information, or data, or carry out actions with the information, such as calculating numbers or organising words. Thus a computer can

  • Receive information
  • Store Information
  • Change Information
  • Process Information

The representation of information in a formalised manner suitable for communication, interpretation and processing, generally by a computer system is called Data. The data can be Raw Data or processed Data. Raw data refers to unprocessed information.

Types of Computers:

The Computers can be generally classified by size and power, although there can be considerable overlap in these types. The major types of the computers are as follows:

  1. Mainframe Computers
  2. Mini-Computers
  3. Workstations
  4. Computer Networks
  5. Personal Computers

Mainframe computers

  • Mainframe computers are large-sized, powerful multi-user computers that can support concurrent programs.
  • They can perform different actions or ‘processes’ at the same time.
  • Mainframe computers can be used by as many as hundreds or thousands of users at the same time.
  • For Example, the Large organisations may use a mainframe computer to execute large-scale processes such as processing the organisation’s payroll.

Mini Computers:

  • Mini-computers are mid-sized multi-processing computers.
  • They can perform several actions at the same time and can support from 4 to 200 users simultaneously.
  • In recent years the distinction between mini-computers and small mainframes has become blurred. The distinction generally depends upon how the manufacturer wants to market its machines.
  • Companies and organizations may use a mini-computer for such tasks as managing the information in a small financial system or maintaining a small database of information about registrations or applications.


  • Workstations are powerful, single-user computers.
  • Workstations have the capacity to store and process large quantities of data, but they are only used by one person at a time.
  • However, workstations are typically linked together to form a computer network called a local area network, which means that several people, such as staff in a bank office, can communicate with each other and share electronic files and data.
  • A workstation is similar to a personal computer but is more powerful and often comes with a higher-quality monitor. In terms of computing power, workstations lie in between personal computers and mini-computers. Workstations commonly support applications that require relatively high-quality graphics capabilities and a lot of memory, such as desktop publishing, software development and engineering applications.

Computer network:

  • A grouping of computers and peripherals connected together by telecommunications links to enable a group of users to share and exchange information is called a Computer Network.

Personal computers

  • Personal computers (PCs), also called microcomputers, are the most popular type of computer in use today. The PC is a small-sized, relatively inexpensive computer designed for an individual user.
  • Today, the world of PCs is basically divided between IBM-compatible and Macintosh-compatible machines, named after the two computer manufacturers.
  • Computers may be called ‘desktop’ computers, which stay on the desk, or ‘laptop’ computers, which are lightweight and portable.
  • Organisations and individuals use PCs for a wide range of tasks, including word processing, accounting, desktop publishing, preparation and delivery of presentations, organisation of spreadsheets and database management.
  • Entry-level PCs are much more powerful than a few years ago, and today there is little distinction between PCs and workstations.

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