Sound card external boxes that plug into the computer via USB.

1. A sound card (also known as an audio card) is a computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs.
2. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education, and entertainment
3. Sound cards usually feature a digital-to-analog converter (DAC), which converts recorded or generated digital data into an analog format. The output signal is connected to an amplifier, headphones, or external device using
4. An important characteristic of sound cards is polyphony, which is more than one distinct voice or sound playable simultaneously and independently, and the number of simultaneous channels
5. Sound cards for computers compatible with the IBM PC were very uncommon until 1988, which left the single internal PC speaker as the only way early PC software could produce sound and music
6. The Sound Blaster line of cards, together with the first inexpensive CD-ROM drives and evolving video technology, ushered in a new era of multimedia computer applications
7. Most new soundcards no longer have the audio loopback device commonly called "Stereo Mix”  that was once very prevalent and that allows users to digitally record speaker output to the microphone input
8. Professional soundcards are special soundcards optimized for real-time (or at least low latency) multichannel sound recording and playback, including studio-grade fidelity
9. USB sound "cards" are mostly external boxes that plug into the computer via USB. They are sometimes called audio "interfaces" rather than sound-cards,
10. Soundcards using the PCMCIA cardbus interface were popular in the early days of portable computing when laptops and notebooks did not have onboard sound.