Most PCs are typically equipped for multimedia. They can play sounds, music, and speech. The sound card processes the information and outputs the signal to the speakers.
The sound card plugs into a slot on the motherboard or is built right into the board. Many PCs now include a basic sound processor built into the motherboard and a card used for higher end sound and features are desired. With a basic sound card a microphone, speakers and an auxiliary sound source can be connected to it. More advanced cards support additional features such as surround sound.