Files with the AL extension are mainly used by the QuickTime Player media player. AL files are used to store audio content. The data in these files is generated using the A-law algorithm, which is used in 8-bit PCM digital communication systems (mainly telephony). The algorithm allows to modify the dynamic range of the analog signal in such a way as to optimize its digitization.

AL files contain compressed audio data and in Europe they use the A-law algorithm G.711 developed by ITU-T.