有 (yǒu) — possession and existence
有 yǒu is the second most useful verb in beginner Mandarin (after 是). It does the work of two English verbs: 'to have' when the subject possesses something, and 'there is / there are' when describing what exists at a place. 我有一本书。 = I have a book. 桌子上有一只猫。 = There's a cat on the table — same verb, completely different feel. The huge trap: 有 is the one verb that does NOT take 不. The negation is 没有 méiyǒu — the only place you'll see 没 in beginner Mandarin. Memorize this exception now.
有 = to have
Subject + 有 + (number + measure word) + thing. 我有一本书。 = I have a book. 她有两只猫。 = She has two cats. 我们有三个朋友。 = We have three friends. 你有妈妈吗? = Do you have a mom? Notice: a noun after 有 almost always carries a number+measure word (or 很多 = many). Bare 我有书 sounds odd unless you mean 'I have books (in general)'.
有 = there is / there are
Flip the structure: place + 有 + thing. The place comes FIRST and the thing comes after. 桌子上有一本书。 = There's a book on the table. 学校里有很多学生。 = There are lots of students at the school. 家里有猫吗? = Are there cats at home? This is the standard way Mandarin describes what's around. English speakers often want to start with 'there', but in Mandarin the LOCATION leads. Compare: 'on-table-have-one-MW-book'.
Negation: 没有, never 不有
有 is the only verb that doesn't take 不. The negative is 没有 méiyǒu — written 没 + 有, said as one word. 我没有书。 = I don't have a book. 桌子上没有猫。 = There isn't a cat on the table. In casual speech you can drop 有 and just say 没: 我没书。 is fine, 没书 alone too. NEVER 不有 — that's a guaranteed wrong-mark. Also: 没 by itself is the past-tense negator for other verbs (我没去 = I didn't go), but for now just lock in 没有 as the negation of 有.
The yes/no question and 有没有
Two ways to ask 'do you have?'. The lesson-3 way: statement + 吗. 你有妈妈吗? = Do you have a mom? The new way: V-not-V (有没有). 你有没有妈妈? Same meaning. The V-not-V pattern works with most verbs: 你是不是学生? = Are you a student? It's slightly more common in spoken Mandarin than the 吗 version when asking about possession or existence. Pick whichever feels natural.
What 有 doesn't do
有 is NOT used with adjectives ('I'm hungry' is 我饿 or 我很饿, not 我有饿), and not with feelings or states the way English uses 'I have a headache'. For age, you don't use 有 either — number + 岁 is enough (lesson 5). 有 is for concrete possession and concrete existence. Stick to those two roles.
