Clearly tapping out to signal submission in locks and chokes — the single most important safety rule in grappling.
You tap two or three times clearly on your partner or the mat; if that's impossible, say 'tap' out loud. The heart of this rule is cultural rather than technical: in grappling, submitting isn't defeat, it's the precondition for training again tomorrow. Torn ligaments and damaged elbows almost always come from tapping too late — out of pride, or because someone missed the moment a technique locked in. Tap early, especially with leg locks and neck techniques where the warning window is very short. And the obligation runs just as strictly the other way: on a tap you release immediately, no exceptions, no delay.