How to Identify Essential and Nonessential Clauses

Clauses are the foundation of writing. Without them, you’d only have a jumble of words with no clear meaning. Therefore, it makes sense to understand what they are as well as the types. Discussing clauses is also the perfect time to address another grammar issue that goes hand in hand with them, the use of which and that.

What Are Clauses?

Clauses are simply a grammatical construction that consists of a subject and verb. You may also see them called restrictive and nonrestrictive. We prefer the former since its meaning is better understood. They can stand on their own as independent structures or take on a phrase function within a sentence.

Essential Clauses

The operative word is essential. That means it’s vital for understanding the correct meaning of the sentence. Its omission adds uncertainty and ambiguity. It’s important to remember that essential refers to the meaning of the sentence and not a sense of urgency. The clause identifies a particular thing or fact important to the complete thought.


  • The job that Jack lost has been filled by someone else.
  • The classic car that he bought last month is worth over $10,000.


You can think of nonessential clauses as an aside. They include added information for interest only. But, they are not crucial to understanding the meaning of a sentence. Nothing is lost by their omission because the original meaning of the sentence remains intact even without the nonessential clause.


  • Jack, who used to be a firefighter, won the 5k race.
  • The woman, who lives in Dallas, was the winner of the lottery last night.
  • The town, where tourists like to visit, has the smallest year-round population.

Construction of Clauses

You may have noticed a few subtle grammar differences between the examples of essential and nonessential clauses. The former uses identifiers that specify the clause such as that, who or where. Also, there are no commas cutting it off from the rest of the sentence. That makes it seem more a part of the sentence.

In the latter which replaces the word, that. You may also see who or where used, but the difference lies with the fact that there are commas around the clause. That is a visible tip-off that it is nonessential to the complete thought.

How Do You Decide If It’s Essential?

Distinguishing between essential and nonessential clauses is crucial to maintaining the intended meaning of a sentence. Part of the difficulty lies with the use of that and which. Modern usage has blurred the distinction between the two. It’s a ubiquitous error. Correct grammar specifies their use though it sometimes gets cast aside.

The best way to determine the type of clause is simply to remove it and compare it to the original sentence. If the meaning is altered or becomes unclear, the clause is essential. Then, you can add the right pronoun and commas as necessary to make it correct. Unlike other grammar errors, the correct use of essential and nonessential clauses means understanding its context.

Vincent D'Eletto

Vincent D'Eletto

Hey, I'm Vin. Founder and CEO of I create content that ranks really well on search engines for our clients. I'm also deeply involved with the SEO community; maintaining a portfolio of successful, profitable affiliate websites. You can find me playing guitar, drinking scotch, and hanging out with my German Shorthaired Pointer when I'm not working!