Restrictive Clause:
* Definition: A restrictive clause provides essential information that clarifies the noun it modifies. Without it, the sentence would be unclear or incomplete.
* Comma Usage: No comma before "which".
* Example: "The book which I bought yesterday is about history." (The clause "which I bought yesterday" identifies the specific book being discussed. Removing it makes the sentence incomplete.)
Non-Restrictive Clause:
* Definition: A non-restrictive clause adds extra, non-essential information about the noun it modifies. The sentence makes sense even without the clause.
* Comma Usage: Comma before "which".
* Example: "The book, which I bought yesterday, is a bestseller." (The clause "which I bought yesterday" provides extra information about the book but isn't essential to identifying it.)
Key Points:
* "That" vs. "Which": While both can introduce restrictive clauses, "that" is generally preferred. "Which" is more common in non-restrictive clauses.
* Context: The context of the sentence will help you determine if the clause is restrictive or non-restrictive.
If you're unsure, it's often safer to omit the comma. You can always reread your sentence to check if the clause is truly necessary for understanding the noun it modifies.