A sound card is a piece of computer hardware used to create and output audio signals. It is also known as an audio card, audio adapter, or sound board. This device adds or improves sound capabilities to a computer system, allowing for the playback and recording of audio.

Sound cards were originally introduced in the early 1980s, and were used primarily for video game audio. However, as desktop publishing and multimedia capabilities became prominent, sound cards quickly became a necessary component for all computer systems.

Sound cards are typically installed inside the computer system and connect to the motherboard through a PCI or PCIe slot. Alternatively, many motherboards come with built-in sound cards, but these will often be limited in their capabilities.

The main functions of a sound card are to play back audio and record audio. Playback can include music, sound effects, and even spoken words. Sound cards can also enhance audio for video playback by decoding digital audio formats such as Dolby Digital and DTS.

Recording capabilities can range from basic microphone input to professional-quality audio recording using a specific type of microphone or instrument. Additionally, sound cards can be used as a MIDI controller to produce digital music.

Sound cards can also come with additional features such as multiple audio outputs, support for surround sound, and advanced audio processing capabilities.

Overall, a sound card is a crucial component for any computer system that is used for entertainment, multimedia production, or music creation. It enhances the audio capabilities of the computer and provides a higher level of experience for users.