Definition & Meaning of "in the can"

What is the origin of the idiom "in the can" and when to use it?

The idiom "in the can" has its origins in the early days of film-making, when movies were recorded on actual film reels. After a scene was successfully filmed, the film reel containing the footage was placed in a can or film canister for storage and later processing. Over time, the phrase has been adapted to indicate that a task or project is finished or that something is completed and ready for use.