Countdown

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For the game show, see: Countdown (game show), and the music television show, see: Countdown (music show).

A countdown is the backward counting to indicate the seconds remaining before an event, such as a launch, the start of a race, and New Years. The last ten seconds are usually counted down aloud "10-9-8-7-6-5-4-3-2-1-Liftoff."

The "T minus Time" is the time before launch, e.g. "The countdown was held at T minus 5 minutes for 3 minutes and 40 seconds".

The first known use with respect to launching a rocket occurred in Fritz Lang's 1929 film Frau im Mond. In the film, after each number the words "seconds to go" was repeated.