A sound card (also referred to as an audio card) is a peripheral device that attaches to the ISA or PCI slot on a motherboard to enable the computer to input, process, and deliver sound.
The sound card's four main functions are: as a synthesizer (generating sounds), as a MIDI interface, analog-to-digital conversion (used, for example, in recording sound from a microphone), and digital-to-analog conversion (used, for example, to reproduce sound for a speaker). The three methods of sound synthesis are through frequency modulation (FM) technology, wavetable, and physical modeling.