Summer 2015
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That, Which, Who:
Essential and Non-Essential Clauses
Essential Clauses:
Essential clauses (restrictive, or relative, clauses) includes information that is important to the meaning
of the sentence.
That:
The word “that” refers to objects or places and is the biggest indicator of an essential clause (versus
“which,” which is a tell-tale of a non-essential clause). It introduces a descriptive or informative phrase
that adds important details to a sentence.
Example: The book that Dr. Doright left in the dining hall showed up on his desk today.
Non-essential Clauses:
Non-essential clauses (non-restrictive clauses) include information that is not important to the meaning
of the sentence. A comma always precedes a non-essential clause.
Which:
The word “which” introduces information that is not necessarily key or essential to understanding
what the writer wants to say and is the biggest indicator of a non-essential clause.
Example: Dr. Doright left the book, which was a birthday gift, in the dining hall.
Who—Essential and Non-essential:
Who always refers to people, not objects or places and can be used as to offset essential and non-
essential clauses.
Examples: Dr. Doright, who teaches Composition 1101, has a terrific sense of humor. (Non-essential)
The man who backed his car into me drove away without stopping to give me his insurance
information. (Essential)
