Back-timing

Back-timing means working backwards from a fixed out time — a break, a hand-off, or the top of the hour — through the running order, so that each item gets a "must start by" time. Where a normal forward timing tells you how long things last, back-timing tells you when they have to happen to land the out.

It's the professional way to keep a live show on time, because being right on total runtime doesn't help if you blow an internal break by two minutes. You back-time to every hard out, not just the end of the show, and a show clock counts down to each one so the crew can adjust on the fly.