Files with the extension .BAND are project files created using 'GarageBand' a software application that allows users to create music or podcasts.

GarageBand is a streamlined digital audio workstation (DAW) which can record and play back multiple tracks of audio.

The .BAND file contains the saved music project.

* GarageBand is included with 'iLife' a multimedia suite of software applications bundled with all new Macintosh computers.