Who, which or that?

Who, which and that introduce relative clauses: extra information about a noun.

Who is for people

“The girl who won the race is my cousin.”

Which is for things and animals

“The book, which was on the table, had disappeared.”

That is for things (and sometimes people)

“The book that I lent you is overdue.”

That or which?

In British English the two often overlap, but here is a useful rule:

• Use that (no commas) for information you need to identify the noun: “The bike that has a flat tyre is mine.” (Which bike? The one with the flat tyre.)
• Use which with commas for extra information you could remove: “My bike, which is red, has a flat tyre.”

The comma test

If you can put the clause in commas and remove it without changing which thing you mean, use “which”.

Try it: complete these: “The teacher ___ marked my essay was strict.” “Our car, ___ is ten years old, broke down.”