21 Commas with Essential and Nonessential Elements
KEY CONCEPTS
An essential element can be a clause containing information that a reader must know to interpret a sentence. If you remove the essential element from a sentence, the meaning of the sentence changes or becomes unclear.
With essential elements, you do NOT use commas.
Police will arrest any protesters who remain after midnight.
(Police will arrest a subset of protesters, those who remain after midnight, but not all protesters. The part after protestors – “who remain after midnight” – is essential, so commas must not be used there.)
Writers sometimes use the pronoun that to introduce an essential element if that follows an inanimate noun,.
The two ad campaigns that yield the most online traffic will win an award.
(The pronoun that follows the inanimate or non-human noun campaigns.)
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Conversely, a nonessential element can be a clause providing additional information that is not essential to the structure of a sentence.
Nonessential elements should be set apart with commas.
The coach, who won three state championships in 20 years, will retire after the season.
(Removing the information about three state championships will not affect the meaning of the remaining sentence saying that the coach will retire after the season, so the nonessential element is set off by commas.)
A nonessential elements will often begin with the pronoun which if it follows an inanimate object.
One humorous ad campaign, which yielded 2 million online views, won top prize.
(The pronoun which follows the inanimate or non-human noun campaign.)
Here’s a quick foundational question that can further help you understand essential and nonessential elements in sentences.
Now let’s try a follow-up question.
In grammar, the terms essential and nonessential refer to how the sentence is constructed and not the value of the content. You should place nonessential elements within commas.
Here’s another question.
The next question involves an object instead of people.
In the flip card above, the embedded clause (which weighs 70 pounds), depends on the core sentence (The refrigerator costs $500). Some English teachers use the term dependent (or subordinate) clause to describe a nonessential element with a subject and a verb. In this online guidebook we’re primarily focusing on correct usage and not terminology.
Based on the previous flip cards, here is a true-false question for you.
Here are two key takeaways from this lesson:
1. Do NOT use commas for essential elements. These elements often begin with the relative pronouns that and who.
The issue that matters most to voters is the economy.
The players who appeared in every game received a special award.
2. You should use commas for nonessential elements. These elements often begin with the relative pronouns which and who.
The economy, which is the top issue for most voters, may decide this election.
The vice president, who arrived today, will be here for six days.
Now, I want to share a common error with you.
We’ve spent much of this chapter studying how to use that and which because of frequent errors involving those two relative pronouns.
Also, remember that the relative pronoun who can be used to start an essential element or a nonessential element. Here are two closing examples:
Essential – no commas
The only council member who complained about the budget is not here today.
Nonessential – set apart in commas
Council member Sharon Silka(comma), who complained about the budget(comma), is not here today.
MORE PRACTICE FOR PROFICIENCY
Below are additional usage questions based on this chapter. These questions may help you study for course assignments or a proficiency exam.
Additional Practice
WRITING EXERCISE
1. Write your own sentence using that to introduce an essential element.
2.Write your own sentence using which to introduce a nonessential element.
3. Write your own sentence using who to introduce an essential element.
4. In two tightly constructed sentences, explain your key takeaway from this chapter. Do not use any first-person pronouns (such as I, me, my or mine) in your writing.
