このツールとは？
The stopwatch tool measures elapsed time with start, pause, and reset. You can record laps to see the duration of each segment.
なぜ使う？
Useful for timing exercise, study, or work segments, or for simple timing, with no app install—just the browser.
使い方
Press start to begin; elapsed time increases. Use pause to stop and start again, or reset to clear. Press lap to record the time at that moment.
The stopwatch runs only while the tab is open; closing the tab resets it.