Monitors are the most common form of output used by computers. The two most common types of displays are CRT (cathode ray tube) and LCD (liquid crystal display). The computer monitor's job is to convert the signals taken from the video adapter and turn them into a projected image comprised of thousands of pixels (short for picture elements).

The second most common form of computer output is a printer. A printer converts electronically stored files into hard copy by applying ink to paper. Printers are classified by how they put ink on the paper. The most common are:
Inkjet: An inkjet printer sprays droplets of ink onto paper via a nozzle.
Dot Matrix: Dot matrix printers use a set of small pins to stamp dots out of an ink-coated ribbon.
Laser: Laser printers are very complex. They use static electricity to produce documents.

A speaker is basically the opposite of a microphone. It receives analog audio from the sound card and turns it into sound vibrations that we can hear.