Monitor: The display screen, color monitors can display anywhere from 16 to over 1 million different colors. Often known as RGB monitors, because they accept three separate signals - red, green, blue. Monitors like television screens are measured in diagonally in inches, the distance from one corner to the opposite corner. The resolution of a monitor indicates how densely packed the pixels are. In general, the more pixels (often expressed in dots per inch), the sharper the image. Most modern monitors can display 1024 by 768 pixels, the SVGA standard. Sometimes it is known as a Visual  Display Unit (VDU).

Mouse: A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface. Its name is derived from its shape. As you move the mouse, the pointer on the display screen moves in the same direction. Windows use a Graphical User Interface (GUI) which allows a mouse to point at an icon that represents what you want to do. Mice contain (normally) two buttons, and a scrool wheel which is useful for long documents. The left button is used for selecting and the right button is used for shortcut menus. Some mice are cordless and communicate by optical sensors.

Printer: A device that prints text or illustrations on paper. Printers are classified by their quality; the speed of printing and the resolution; the faster and higher the better. (Resolution is the amount of dots printed per square inch).                                                                There are many different types of printer used for different purposes:                   Daisy wheel: a hammer presses the shape of each character against an ink ribbon, it cannot print images,                                                                                                              Dot matrix: similar to the daisy wheel, but pins are used so that characters and images can be printed,                                                                                                                                              Ink-jet: sprays ink at a sheet of paper, can produce high-quality text and graphics photo quality,            Laser: produce very high quality text and graphics, they use heated powder, the same as photocopiers. A Plotter is a specialist pronter for architects and engineers etc, it produces very large detailed drawings.

Scanner: A device that can read text or illustrations printed on paper and translate the information into a form the computer can use. A scanner works by digitizing an image, the resulting matrix of bits, called a bit map, can then be stored in a file, displayed on a screen, and manipulated by programs. The denser the bit map, the higher the resolution, meaning a larger or sharper image. Typically, scanners support resolutions of from 72 to 600 dots per inch (dpi). The scanner normally used in a system is known as a flatbed scanner, like a photocopy machine. It has a glass surface on which you lay paper, magazines, or other documents that you want to scan. The scanner does half the work of a photocopies. Some scanners are part of the same box as a printer and can be used as a photocopier.

Sound:Loud Speakers: Are essential for listening to the output from films, games, music and other programs that produce audio sound.

Microphones: are used for recording external sound onto the computer.

Some internal devices may not be present in a system or can be added on upgrading. Although normally found inside a computer the following are peripheral devices:

External Modem:

External Floppy Disk Drive:

External CD-ROM Drive: