Telling someone not to: 别 and 不要 + verb

To tell someone not to do something, put 别 (bié) or 不要 (bú yào) before the verb: 别说话 (don't talk). 不要在这儿吃东西 (don't eat here).

别 is shorter and more common in speech. 不要 is a bit more formal (signs, instructions).

别 … 了 often means “stop…-ing”: 别说了！ (stop talking / that's enough!).

Everyday phrases: 别忘了！ (don't forget!), 别进来 (don't come in).

Note: 不 + verb states a fact (“he doesn't eat”), 别 gives an order (“don't eat!”).