A sound card is an internal computer component that processes audio files in order to provide high-quality playback through computer speakers. A sound card plays voice as well as music files, and can handle various audio file formats including .wav, .mp3 and .cda to name but a few. The typical sound card has an interface available at the back of the computer with various input and output ports. The quality of the sound card and speakers both affect the overall sound quality of the computer system. Speakers plug directly into the back of the sound card.

A sound card also has a line-in port for listening to or recording from an external device such as a digital audio player. If the source device does not have a line-out port to connect to the sound card, a stereo cable can be run from the headphone jack on the source device to the line-in port on the sound card. Software configurations may be required to hear the device playing.

Another port on a sound card is the microphone port. By plugging in an external mic, one can record notes, lectures, daily personal logs, audio blogs or podcasts. For private listening, every sound card features a headphone jack, which offers the perfect way to enjoy MP3s, DVDs or other audio files without disturbing others.

A sound card typically comes with proprietary software and drivers, though standard Microsoft operating systems automatically detect and load drivers for popular cards. The software interfaces with the sound card to allow the user to set parameters and controls, and to perform checks on the hardware. It might also come with tools for recording, burning, editing or composing.

Advanced sound cards come with added versatility for audiophiles. The sound card might include a digital sound port, midi interface or Sony-Philips Digital Interface Format (SPDIF) in/out ports. Some include a front bay interface that might feature a second line-in, instrument ports for recording original music, a headphone jack with its own volume control, Firewire or other options. Having these ports at the front of the computer in a bay, rather than at the back, is highly convenient for using the computer as a personal recording studio.

Generally, more expensive sound cards come with advanced software programs for editing and recording. They also support surround sound for a high-quality audio experience. This is important to audiophiles and gamers alike.

Many motherboards today have built-in sound cards. These can be disabled in order to use a superior third-party sound card purchased and installed separately. However, a built-in sound card is likely adequate for those less fanatic about their sound quality. Sound cards range in price from about 20 to 400 US dollars (USD). They are available everywhere computer components are sold.