1. Essential and Nonessential Sentence Elements
Comma Rules 3-4
Essential and Nonessential Sentence Elements

2. Essential and Nonessential Sentence Elements
Use a pair of commas in the middle of a sentence to set off clauses, phrases, and words that are not essential to the meaning of the sentence.
Do not use commas to set off essential elements of the sentence.

3. Do not use commas to set off essential elements of the sentence, such as descriptive clauses beginning with “THAT” (and sometimes “WHO”).
Essential elements are part of the primary sentence, and they are needed for clear understanding. Nonessential elements can be removed and the sentence will still make sense.
In other words, if you see the word “THAT” after a noun or verb, chances are that you will NOT need a comma.

4. Examples of clauses beginning with THAT after nouns:
The apples that fell out of the basket are now bruised.
I put the book that I borrowed from you back into your locker.
The tornado that raced through the small town destroyed several buildings and businesses.

5. Examples of THAT clauses following a verb showing mental action:
The football player wished that a cool breeze would move across the practice field.
I contend that it was wrong to mislead her.
The teacher believes that students will be able to raise their six weeks’ grades by ten points if they reread each assignment.

6. Other Examples The baby wearing the pink jumpsuit is my niece.
The political candidate who raises the least money usually loses the election.

7. A nonessential sentence element is like a detour; it takes an optional road, with each end shown by a comma. Example: That road to Tucson, ________________________, has a short detour under construction since 2011

8. Nonessential Elements Examples
That Tuesday, which happens to be my birthday, is the only day I can come.
Tom, the captain of the team, was injured in the game.
It is up to you, Jane, to finish.
She was, however, too tired to make the trip

9. Essential and Nonessential Sentence Elements More examples
The baby wearing a yellow jumpsuit is my niece.
My niece, wearing a yellow jumpsuit, is playing in the living room.