Words : That vs. Which Quiz

That and which are words with very similar usage. Typically, 'that' is used as part of a clause that is restrictive, meaning that the clause is essential to the sentence and without it the meaning of the rest of the sentence would be different. 'Which' is used as part of a clause that may add extra information or a shade of meaning, but is not required in the same way. There is usually a comma before "which."