When do I use "that" versus "which"?

A little morei

The test: can you lift the clause out without breaking the meaning? If yes, it is a which clause, set off with commas — "my bike, which is red, got a flat." If no, it is a that clause with no commas — "the bike that I bought yesterday."

The full entryii

More quick answersiii

• → Do you put a comma before "which"? Usually yes — which introduces extra information, and that kind of clause takes commas on both sides.
• → Is it "the book that I read" or "the book which I read"? In edited American English, "the book that I read." Which sounds natural in British English.