的【de】

的 marks the owner. It goes between the owner and the thing owned, in that order – like English "'s", not like "of".

• × 书的我 → 我的书

"My", "your" and "his" are 我的, 你的, 他的 – the ordinary pronoun plus 的, with no separate possessive word to learn.

的 with no noun after it

Drop the noun when it is obvious and 的 stands alone, meaning "mine", "yours", "the teacher's".

Where 的 drops

After a pronoun, family members and a handful of close relationships leave it out: 我妈妈, 你哥哥, 他朋友. Keeping it is not wrong, but the shorter form is what people say.

It drops for your home and for a group you belong to as well: 我家, 我们学校, 我们公司.

Ordinary things you own keep 的.

• × 我书 → 我的书