25 minutes of focus, then a short break — the classic Pomodoro technique. Runs in this browser tab; keep it open while you work.
A time-management method: work in focused blocks (traditionally 25 minutes), then take a short break. After a set number of blocks (traditionally 4), you take a longer break. The numbers here default to that but are fully editable.
Yes, switching tabs or apps is fine — the timer keeps counting in the background of your browser. Closing the tab, closing the browser, or reloading the page resets it, since nothing is saved between sessions.
Yes — work, short break, long break, and how many work cycles happen before a long break are all editable before you press start.
No camera involved. It plays a short sound at the end of each phase, and will ask your browser's permission (a normal browser prompt) before showing a desktop notification — it never does so silently.