What is the origin of the idiom "under the wire" and when to use it?

The idiom "under the wire" has its origin in horse racing, specifically in reference to the finish line. In horse racing, a wire was traditionally stretched across the track at the finish line to determine the winner. Jockeys and their horses would strive to cross the finish line under the wire, aiming to be the first to reach it. It is commonly used when referring to completing a task, submitting a document, or achieving a goal just before a designated deadline.