A loop is a section of audio — typically 2, 4, or 8 bars — that repeats without any audible break or gap. Loops are building blocks for music production, allowing producers to quickly assemble arrangements.
Drum loops, bass loops, melodic loops, and percussion loops are the most common types. They're sold individually or in packs, usually tagged with BPM, key, and genre.
Using loops is standard practice in modern production. Many hit records are built on loops — the skill lies in selection, layering, and arrangement.