Band-in-a-Box is a music creation software package for Windows and macOS produced by PG Music Incorporated, founded in 1988 in Victoria, British Columbia. The software enables a user to create any song and have it accompanied by professional musicians playing real instruments. Despite this remarkable accomplishment, reviewers have described the software interface as awkward or outdated. The user enters four basic keyboard inputs consisting of: chords; a key; a tempo; a musical style. The screen resembles a blank page of music onto which the user enters the names of chords (even sophisticated complex ones) using standard chord notation. The software generates a song typically played by four or five studio musicians using those chords; the user can specify whether to create solo parts over these chords as well. The developers have enlisted musicians as supporting instrumentalists to build huge databases of phrases in many styles of music. The software retrieves and customizes groups of musical phrases that are appropriate for soloing or comping over a particular chord at a chosen key, genre and tempo. It can create backgrounds, melodies or solos for almost any chord progressions used in Western popular music, and can play them in any of thousands of different music styles.

Band-in-a-Box was first introduced in 1990 for PC computers and the Atari ST. The creator of the software is a Canadian, Dr. Peter Gannon, for whom "PG Music" is named. Early versions featured only MIDI data often emulating the phrasing of noted musicians. Newer versions also contain recordings (called "RealTracks") of real musicians playing real instruments. (examples below)