Watchlist
Watching a page
Open an article’s Tools tab and press Watch — the row flips to Watching. Press it again to stop. (Tools also holds What links here and Subpages.)
Your watchlist
Watchlist in the account menu is Recent changes filtered down to the pages you watch: every edit to a watched page, with the same chips, times, authors, and size deltas — and nothing else.
Watching needs a verified account; unwatching never does — the star always lets you stop.