In audio, a subgroup is a group of sources (channels, tracks, etc.) that are combined into one bus on a mixer. The term is very closely related to, but not the same as, submix. Subgroups are created for a variety of reasons, most of which have to do with convenience. For example, it is very handy (especially when mixing live) to have sets of common sources grouped together into a subgroup so they can all be controlled with one fader. It is common to create drum sub, a keyboard sub, a backing vocal sub, etc.