A Sound API is a set of programming instructions that allows developers to integrate audio functionalities into their applications. These interfaces enable software to play, record, and manipulate sound, making it easier to create music, sound effects, or voice interactions in games and other multimedia applications. Sound APIs can support various audio formats and provide tools for controlling volume, pitch, and playback speed. Popular examples include Web Audio API for web applications and OpenAL for 3D audio in games. By using these APIs, developers can enhance user experiences with rich audio features.