A stopwatch counts up from zero. Use it for a speech when you need to know how long you have gone, for a lap around a field, or for any job where the end is not chosen in advance. Laps freeze the elapsed time at the moment you press Lap, and the clock keeps going.
Elapsed time is measured from a start timestamp plus the time you spent paused. Leaving the tab does not make the stopwatch count slowly. When you return, the number is the true elapsed time. That matters for a talk you timed while your slides were in another window.
Space starts and pauses. R resets and clears the laps. F fills the screen, which is the right move when a room is watching a speaker. Classroom mode hides everything but the clock. The alarm sounds are for the countdown pages. A stopwatch does not ring by itself, because it has no end until you stop it.
Questions
How do laps work?
Press Lap while the stopwatch is running. Each lap records the total elapsed time at that press. Reset clears the list.
Can I use this as a countdown?
Use a minute timer or the countdown page if you need an end time. This page only counts up.
Does the stopwatch stay accurate in the background?
Yes. It stores the moment you started and subtracts paused time, so it does not depend on a steady stream of ticks.