ALSA or the Advanced Linux Sound Architecture provides audio and MIDI functionalities to the Linux operating system.

ALSA is a collection of several modules. The first is a fully modularized sound driver, which supports modules like autoloading, devfs, isapnp autoconfiguration, and gives complete access to analog audio, digital audio, control, mixer, synthesizer, DSP, MIDI, and timer components of audio hardware.

This software also includes a fully featured kernel-level sequencer, a compatibility layer for OSS/Free applications, an object-oriented C library for enhancing the ALSA kernel driver functionalities for applications - client/server, plugins, PCM sharing/multiplexing, PCM metering, etc. It also offers an interactive configuration program for the driver, and some simple utilities for basic management.

Following are some of the significant features of ALSA:
· Efficient support for all types of audio interfaces
· Fully modularized sound drivers
· SMP and thread-safe design
· User space library for simplifying application programming and providing higher level functionality
· Support for older OSS API
· Binary compatibility for most OSS programs

ALSA is completely free and open source software licensed under GNU GPL.
For the normal user, ALSA and its functions are completely transparent, and there should be little or no need for dealing with ALSA once it has been configured for your machine.

The ALSA package also includes a variety of important tools such as the arecord/aplay programs, the alsamixer, and the aconnect MIDI connection utility.