How do I say 'sorry'?

Chinese has an apology ladder, and climbing too high (or too low) makes the interaction feel off. Here is the practical rule:

• 不好意思 — the 90% apology. Bumping into someone, being slightly late, interrupting, asking a stranger for directions, reaching across the table. It acknowledges the inconvenience without turning it into a moral event.
• 对不起 — the meaningful apology. You hurt someone’s feelings, broke a promise, made a mistake with consequences. This is the apology that expects a response (没关系).
• 抱歉 — the formal register. Emails, customer service, written apologies. Carries regret without the interpersonal weight of 对不起.

The common foreign-learner mistake is overusing 对不起 because it maps most directly to “sorry.” In practice, 不好意思 handles most of daily life, and saving 对不起 for when you mean it makes your Chinese more socially accurate.