Work Area

A range inside the timeline ruler that defines your playback area. It starts as the full comp, but you can adjust it to only play back a certain region of the timeline.

Press B to set the start to the playhead, N to set the end. Composition → Reset Work Area restores the full range. Or just double-click any middle part of the work area bar to reset it.

If the playhead is outside the work area when you press Space, playback jumps to the work area start and starts playing from there.