Nonessential Clause
A nonessential clause adds information without restricting which person or thing the sentence identifies. In standard edited English, it is set off with commas when embedded in a sentence; an essential/restrictive clause is not treated the same way.
A nonessential clause gives extra, nonrestrictive information and is normally set off with commas. If removing the clause changes which person or thing you mean, the clause is essential/restrictive instead.
Key details
Important caveats
Scope Boundary
“Nonessential” is a grammatical/semantic label for the clause’s role in that sentence; it does not mean the information is unimportant in every communicative sense.
Further guidance
Application
Test whether the noun is already fully identified without the clause. If yes, the clause is nonessential and usually takes surrounding commas.
Core Rule
Set off a nonessential clause with commas because it adds information without restricting the identity of the noun it modifies.
Practical Application
Set off a genuinely nonessential/nonrestrictive clause with commas in standard edited prose. Before adding or removing commas, test whether the clause merely adds information or is needed to identify which person or thing the sentence means.
Reader Check
If you remove the clause, does the sentence still identify the same person or thing?
Worked Example
“My brother, who lives in Delhi, is visiting” treats the clause as extra information. “The employee who filed the report is visiting” uses the clause to identify which employee and therefore does not set it off as nonessential.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Commas with Nonessential Elements — Purdue OWL (opens in a new tab)Purdue Online Writing Lab · Direct guidance distinguishing essential/restrictive from nonessential elements and their comma treatment.