Is this a run-on sentence?
Overcome with joy, Mrs. Cohen told her husband the exciting news about her promotion.
no yes
A sentence is a group of words that expresses a complete thought.
The band I'm in has been rehearsing daily because we have a concert in two weeks.
A run-on sentence is formed when two sentences are run together, joined by just a comma or by no punctuation at all. If only a comma is used, the run-on is called a comma splice.
The band I'm in has been rehearsing daily, we have a concert in two weeks.
The band I'm in has been rehearsing daily we have a concert in two weeks.
There are several ways to fix a run-on sentence:
Use stronger punctuation, such as a period or a semicolon.
The band I'm in has been rehearsing daily. We have a concert in two weeks.
The band I'm in has been rehearsing daily; we have a concert in two weeks.
Use a comma and a coordinating conjunction to create a compound sentence. Coordinating conjunctions include and, but, or, and so.
The band I'm in has been rehearsing daily, and we have a concert in two weeks.
Use a subordinating conjunction or a relative pronoun to create a complex sentence. Subordinating conjunctions include after, although, as, because, before, if, since, unless, until, when, and while. Relative pronouns include that, which, who, whom, and whose.
The band I'm in has been rehearsing daily since we have a concert in two weeks.
This is not a run-on sentence. It is not formed from two sentences that have been run together without appropriate punctuation.
Overcome with joy, Mrs. Cohen told her husband the exciting news about her promotion.