请坐。

You use it the moment someone enters your space. You can say it while gesturing toward a chair. It is often paired with a smile. If you want to be extra polite, add a name first. For example, 王先生，请坐 (Mr. Wang, please sit). It is short, so your tone of voice does the heavy lifting.

Use it when a guest arrives at your house. Use it at the start of a business meeting. Use it if you are a waiter seating customers. It is perfect for any situation where someone is standing and you aren't. It bridges the gap between a greeting and a conversation. It shows you are a thoughtful and attentive host.

Don't use it if the person is already sitting. That would just be confusing! Avoid using it with very close friends in a bossy way. With best friends, a casual 坐吧 (zuò ba) feels more natural. Also, don't scream it across a crowded room. It is a phrase meant for close-range hospitality, not a command from a distance.

In Chinese culture, being a good host is a point of pride. Offering a seat is the first step of "The Three Pleasures" of hosting. First, you invite them in. Second, you say 请坐. Third, you offer tea. This sequence is deeply ingrained in social etiquette. Even in modern, fast-paced cities, this small gesture remains a pillar of politeness.

If you want to sound even more formal, try 请入座 (qǐng rù zuò). This sounds like something you'd hear at a wedding or banquet. For a warmer, friendlier vibe, use 快坐下 (kuài zuò xià). This means "quickly sit down" and implies you care about their comfort. If you are feeling very casual, just say 坐 (zuò) with a friendly hand wave.