的【de】

的 links a description to the noun it describes. Whatever modifies the noun goes in front of it, with 的 in between.

The modifier comes first however long it gets. English can hang a description off the end of a noun ("a room with a view"); a 的 phrase always goes before it.

A whole clause as the modifier

A verb phrase or a full clause sits before the noun, exactly where an adjective would. This is where English "who", "that" and "which" go.

• × 人昨天来的 → 昨天来的人

When 的 drops

A one-syllable adjective in a common pairing fuses with the noun and needs no 的: 好人, 新书, 大城市, 小狗. Add 很 and 的 comes back: 很好的人.

Two-syllable adjectives usually keep it: 漂亮的城市, 安静的地方. A few everyday pairs drop it, like 漂亮衣服, but adding 的 is never wrong.

Noun modifying noun

的 links two nouns as well, where English uses "of" or a noun in front: 中国的历史, 明天的课.

Nationalities and materials fuse without 的: 中国人, 木头桌子.