Here's the breakdown:
* Nonessential subordinate clause: A clause that provides extra information but is not necessary for the meaning of the sentence. It can be removed without changing the core meaning of the sentence.
* Independent clause: A complete sentence that can stand on its own.
Examples:
* Incorrect: My dog, who is a golden retriever loves to play fetch.
* Correct: My dog, who is a golden retriever, loves to play fetch.
* Incorrect: The car which is red was parked in the garage.
* Correct: The car, which is red, was parked in the garage.
Why commas are important:
* Clarity: Commas help to separate the nonessential clause from the rest of the sentence, making it easier to understand the meaning.
* Flow: Commas create a smooth flow of reading by indicating a pause in the sentence.
Exceptions:
* If the nonessential clause is very short (typically just a few words) and doesn't create much of a pause, it might be acceptable to omit the commas. However, it's generally best to use them for clarity.
* If the nonessential clause is at the beginning or end of the sentence, you'll only need a comma after the clause (at the beginning) or before the clause (at the end).
In summary, using commas to set off nonessential subordinate clauses is a crucial punctuation rule that ensures clarity and proper sentence structure.