Stems
A song bounced down to a handful of submixes — drums, bass, vocals, everything else — instead of the full multitrack session.
A DAW session can run to a hundred tracks, and whoever receives it rarely owns the same plugins. Stems are the compromise: each group is exported as its own audio file from the same start point, so the files sum back to the original mix. They are used for stem mastering, for remixes and in film, where dialogue, music and effects are kept apart for dubbing.
In 2015 Native Instruments launched the Stems format, four stems in a single MP4 file aimed at DJs. Then machine learning arrived: Deezer's Spleeter in 2019 and Meta's Demucs can split a finished mix into stems out of thin air. It works surprisingly well, and the labels have yet to decide whether they like it.