ALSA, or the Advanced Linux Sound Architecture, is a software framework and part of the Linux kernel that provides an interface for sound card drivers. It enables audio playback and recording on Linux-based systems, allowing applications to access audio hardware efficiently. ALSA supports a wide range of audio devices and offers features like multi-channel audio, software mixing, and low-latency audio processing. It is commonly used in various Linux distributions and is essential for applications that require sound, such as media players and communication software.