Video cards produce the image seen on a computer monitor. A video card's job is to turn instructions from the computer and transform them into the appropriate arrangement of images and text. Video cards have changed massively over the past 20 years, and today's video cards feature options such as 3D processing devices and TV tuners.

A sound card works similarly to a video card, except its output is sound, rather than an image. Sound cards can take audio from the outside world and feed it to the computer. They also possess the ability to produce sound on their own. Furthermore, using the MIDI language, sound cards can be "played", similar to a keyboard synthesizer.

A modem connects a computer to a remote computer by way of telephone lines. A modem turns telephone line signals into data the computer can understand, and then turns data into signals that a telephone line can accept. Modems are commonly used for Internet browsing and email.