Coordinating Conjunctions in Grammar
Use a coordinator to connect parallel grammatical units. When it joins two independent clauses, a comma commonly precedes the conjunction in standard edited prose; when it joins only words or phrases, that clause-level comma rule does not automatically apply.
Coordinating conjunctions link units of comparable grammatical status, such as words, phrases, or clauses. Common English coordinators include and, but, or, nor, for, so, and yet; punctuation depends on what the conjunction is joining.
Key details
Important caveats
Title Case Boundary
Do not use this grammar rule to decide title capitalization. The existing Coordinating Conjunctions in Titles guide owns that separate style question.
Further guidance
Clause Coordination
When both sides can stand as independent clauses, standard sentence punctuation commonly uses a comma before the coordinator: “The test ended, but the analysis continued.”
Parallel Status
Coordinate the same kind of grammatical unit when possible. Mismatched structures can make the sentence harder to parse even if the conjunction itself is correct.
Word And Phrase Coordination
Coordinators can link words (“tea or coffee”) and phrases (“in the office but after lunch”) as well as clauses.
Worked Example
“Mina revised the abstract and checked the references” coordinates two verb phrases. “Mina revised the abstract, and Arun checked the references” coordinates two independent clauses.
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.
- Conjunctions (opens in a new tab)Cambridge University Press · Cambridge shows that subordinating conjunctions introduce subordinate clauses and lists common forms such as although, because, if, when, whereas, and while.
- Sentence Punctuation Patterns (opens in a new tab)Purdue Online Writing Lab · Purdue uses independent-clause patterns to explain complete sentences and how independent clauses are joined, giving a practical writing boundary beyond definition alone.