A visual Display Unit VDU or a monitor

A visual Display Unit (VDU) or a monitor is an output device that accepts video signal direct from a computer. Monitors can display graphics, text and video. The size of a monitor is measured in inches diagonally across the screen; 15, 17, 19 and 21 inch monitors are the most common sizes. A color monitor can display from 16 to over 1 million different colors. Color monitors are sometimes called RGB monitors because they accept three separate signals – Red, Green and blue.

A printer is an output device that produces a printout or hard copy of the output from a computer. There are many types of printer available and which one you choose will depend on how much you want to pay for the printer, the cost of the paper and the ink it uses, what quality of print you want and whether you are going to print just text, graphics, or graphics and text together. The most common types of printer are dot matrix, inkjet and laser printer. The speed of printers can be measured in characters per second (CPS) or pages per minute (PPM), the higher the values are, the faster the printer can produce output.

Inkjet printers work like Dot Matrix printer (the printouts that they produce are made up of patterns of very small Dots) but the printer head has a set of tiny holes rather than pins. As the print head moves across the paper, ink is forced out through the holes to form the image. Inkjet Printers are very quite to operate and can produce good quality printouts of both graphics and text. Relatively cheap color graphics can be printed using a color inkjet.

A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and MFPs, laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor. A laser beam projects an image of the page to be printed onto an electrically charged rotating drum coated with selenium.

A plotter is a vector graphics printing device that connects to a computer. There are two types of main plotters. Those are pen plotters and electrostatic plotters. Pen plotters print by moving a pen across the surface of a piece of paper. This means that plotters are restricted to line art, rather than raster graphics as with other printers. Pen plotters can draw complex line art, including text, but do so very slowly because of the mechanical movement of the pens.

A speaker, or speaker system is an electro acoustical transducer that converts an electrical signal to sound. The term loudspeaker can refer to individual transducers (known as drivers), or to complete systems consisting of a enclosure incorporating one or more drivers and electrical filter components. Loudspeakers, just as with other electro acoustic transducers, are the most variable elements in an audio system and are responsible for the greatest degree of audible differences between sound systems.