的 — whose it is, and which one

的 goes between the owner and the thing owned, in that order — the same order as English the teacher’s name, with 的 where the apostrophe-s would be.

的 is toneless. It is the most common character in written Chinese by a wide margin, and almost none of that is possession — which is the point of the rest of this page.

Dropping it

With people and institutions you are close to, 的 is usually left out. Keeping it is not wrong, but it puts a small distance in the sentence, the way my mother sits differently from the mother of mine.

Family, close friends, your school, your company, your country. Everywhere else, keep it: 我的车, 我的电话.

It also means “the one that”

This is the larger job. 的 attaches any description to a noun — not just an owner, but a whole clause. English does this with that or which and puts it after the noun; Chinese puts it before, and ends it with 的.

Read those right to left and they come out as English. It feels backwards for a long time, and then one day it does not.

With adjectives

A one-syllable adjective attaches directly to the noun with nothing between them. Anything longer — two syllables, or an adjective with 很 in front — needs 的.

的 on its own means “mine”

Leave the noun off and 的 carries it. This is how Chinese says mine, yours, the red one, the one I bought — there is no separate set of words for it.