What is a non-essential clause?

True or False: A non-essential clause should be enclosed by commas?

What is an essential clause?

True or False: An essential clause should be enclosed in commas?

Which type of clause is usually used after a proper noun (Sarah, Eiffel Tower, Dept of Agriculture?

The woman who sells silver jewelry is not here today.

Jack who loves spaghetti refused to try lasagna.

The book which is a Caudill had several holds on it.

The dog that ran away has been found.

The local diner which has amazing chicken nuggets will be closing.

A non-essential clause is a part of a sentence that is not necessary to make a thought complete; it's "decorative rather than defining."

True.

An essential clause is a part of the sentence that is necessary to maintain the overall message/meaning of the sentence.

False! An essential clause needs no commas because it should be read with its subject.

Non-essential

No commas! It is essential to the meaning of the sentence.

The woman who sells silver jewelry is not here today.

Commas! This is nonessential; it is not necessary to understand the meaning of the sentence. It's just an FYI.

Jack, who loves spaghetti, refused to try lasagna.

Commas! It is non-essential. It's just "decorating rather than defining." 

The book, which is a Caudill, had several holds on it.

No commas! It is essential. The reader needs to know "which [dog] of many" is found.

The dog that ran away has been found.

Commas! The dependent clause is not necessary to understand the message.

The local diner, which has amazing chicken nuggets, will be closing.