Twenty-five minutes is the length of one classic focus interval — long enough to make real progress on a task, short enough that your attention doesn't wander. It's most famous as the work interval in the Pomodoro Technique, but it works just as well on its own for any single sprint of focused effort.

If you're looking for the structured work-then-break cycle — 25 minutes on, 5 minutes off, with a longer break every four rounds — see the dedicated Pomodoro timer page, which walks through the method itself. This page is just the plain 25-minute interval on its own.