that and which

Use that to introduce a restrictive clause, which to introduce a nonrestrictive clause. How to choose? Consider whether the meaning of the sentence would be changed if the clause were removed.

Restrictive: Steinbeck wrote the book that made me want to move out west.

Nonrestrictive: The Scarlett Letter, which I read in high school, has been made into a movie.

Use a comma or pair of commas to set off a nonrestrictive clause: Of Mice and Men, which is banned in many school districts, is considered an American classic.

If that appears earlier in the sentence, it is acceptable to use which in place of that to introduce a restrictive clause–but use no comma.

Is that the Steinbeck book which made you want to move out west?