Subject + 不 + Verb
The default way to say someone doesn't do something, or isn't doing something now, or won't do it as a general rule. 不 in front of a verb negates an action that's habitual, present, future-tendency, or willed. It's the most-used negation word in Chinese, and learning when to pick 不 over 没 is one of the first big forks in the road.
Structure
[SUBJECT] 不 [VERB] ([OBJECT])
[SUBJECT] bù [VERB]
How to Think About It
不 negates intent, habit, characteristic, or future inclination — the kinds of 'no' that don't depend on time having passed. 没 negates completion — the action didn't happen. So 我不吃 = 'I don't eat (it)' (won't, don't want to, never do). 我没吃 = 'I haven't eaten / I didn't eat'. If the question is about whether something happened, use 没; if it's about whether someone will or does, use 不.
Examples
我不喝咖啡。
Wǒ bù hē kāfēi.
I don't drink coffee.
他不告公司。
Tā bù gào gōngsī.
He isn't suing the company.
明天我不去上班。
Míngtiān wǒ bú qù shàngbān.
Tomorrow I'm not going to work.
Common Mistake
Learners use 不 with 有 ('to have'), saying 不有. 有 is the one common verb that's always negated with 没, never 不. So 'I don't have' is always 我没有, never 我不有.
我不有时间。
我没有时间。
Don't Confuse With
Subject + 没 + Verb
没 negates a completed past action or the verb 有. 我没去 = 'I didn't go' (it didn't happen). 我不去 = 'I'm not going' or 'I don't go'.
Subject + 别 + Verb
别 is for telling someone NOT to do something (commands). 不 just describes that someone doesn't do it. 别说 = 'don't say (it)'; 不说 = '(I/he/she) doesn't say'.
Subject + 不要 + Verb
不要 is 'don't want to' or a softer 'don't' command. 不 alone is more declarative; 不要 carries an intention or instruction.
Practice
Fill in the blank: 我___喜欢吃辣的。 (I don't like spicy food.)
Show answer
不
Fill in the blank: 他不___中文。 (He doesn't speak Chinese.)
Show answer
说
Arrange: 茶 / 我 / 喝 / 不 (I don't drink tea.)
Show answer
我不喝茶。
Translate to Chinese: She doesn't go to school on Sundays.
Show answer
她星期天不去学校。
Write a sentence with 不 about a habit you don't have.
Show answer
我每天早上不喝牛奶，我只喝水。
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: