Lap time vs. split time
A lap time is how long that single lap took. A split (total) time is the overall time on the clock when you pressed Lap. Runners and swimmers use lap times to check pacing, and split times to compare against a target finish.
Best and worst laps
Once you have two or more laps, the fastest lap is shown in green and the slowest in pink so you can spot pacing changes at a glance.
Keyboard shortcuts and accuracy
Space starts and stops, L records a lap and R resets. The stopwatch reads the browser's high-resolution clock instead of counting frames, so it stays accurate to the hundredth of a second even if you switch tabs.