有 vs 在【yǒu vs zài】

有 and 在 both connect a thing and a place. Which one you use depends on which of the two the listener already knows about.

The first introduces a book the listener didn't know was there. The second is about a book already under discussion, and reports where it is.

The order follows the information

What is known comes first, what is new comes last. 有 starts with the place, so the thing is the news. 在 starts with the thing, so the place is the news.

A definite thing goes with 在

When you're saying where a known thing is, such as 我的书, put it first and use 在. A bare noun with a number, such as 一本书, is new information and goes after 有.

• × 桌子上有我的书 → 我的书在桌子上
• × 一本书在桌子上 → 桌子上有一本书

Negation

是 as a third option

A place followed by 是 and a thing says what occupies that place. 有 leaves room for other things to be there too; 是 says this is what is there.