の

の joins two nouns. A の B is "A's B" or "the B of A": the first noun says whose the second one is, or what kind it is. The owner or the description always comes first and the thing itself comes last.

Japanese has no separate words for "my" or "your". It is 私 plus の, and for "your" the person's name plus の.

The two nouns joined by の act as one noun, so the pair can take は or stand in front of です.

Common mistakes

Two nouns usually need の between them, even where English puts nothing.

• × 日本語先生 → 日本語の先生

An い-adjective goes straight onto its noun, with no の.

• × 大きいの本 → 大きい本

More than ownership

The first noun can narrow the second down in any way: what it is about, where it is or comes from, what it is made of.

The first noun can also say who the second one is.

Whichever noun comes last is the thing you are talking about. Swap the two and the meaning changes.

Leaving out the second noun

When the thing is obvious, the second noun is dropped and の stays: わたくし私の is "mine", たなか田中さんの is "Tanaka's".

Usage notes

These go beyond joining two nouns.

More than two nouns

の can be repeated. Each noun describes the one after it.