Run-On Sentence
First confirm that the problem involves two independent clauses. Then choose a repair that matches the logical relationship: make separate sentences, use a semicolon, use a comma plus coordinating conjunction, or restructure one clause as dependent.
A run-on sentence incorrectly joins independent clauses without adequate sentence-boundary structure. Fix it by separating the clauses, joining them with a semicolon when appropriate, or using a coordinating conjunction with the required punctuation; comma splices and fused sentences are common run-on patterns.
Key details
Further guidance
Conjunction
Use a comma plus a coordinating conjunction when that relation fits: “The server restarted, and the warning disappeared.”
Diagnose
Locate the finite clauses and ask whether each could stand as a complete sentence. If two independent clauses have been joined incorrectly, you have a sentence-boundary problem.
Period
Use two sentences when the ideas do not need a tighter grammatical link: “The server restarted. The warning disappeared.”
Semicolon
Use a semicolon for closely related independent clauses when no coordinating conjunction is needed: “The server restarted; the warning disappeared.”
Worked Example
“The deadline moved we need another review” is fused. Repair it as two sentences, with a semicolon, or as “The deadline moved, so we need another review.”
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.
- Run-ons, Comma Splices, and Fused Sentences — Purdue OWL (opens in a new tab)Purdue Online Writing Lab · University writing-center guidance defining comma splices and showing standard repairs for independent clauses.
- Run-ons, Comma Splices, and Fused Sentences Exercise (opens in a new tab)Purdue Online Writing Lab · Purdue treats fused sentences alongside but distinctly from comma splices, supporting a separate diagnostic/repair intent from the project’s existing Comma Splice guide.