Run-on sentences are sentences that contain too many ideas without proper punctuation. Not all long sentences are run-on sentences. It is perfectly acceptable to join several related ideas in one compound sentence. However, if you don't follow punctuation and syntax rules, a sentence can become a run-on. A simple explanation of run-ons and some run-on sentences examples should clarify this point.
Each sentence has three necessary components:
For more on sentence structure, explore our examples of syntax.
Let's look at how a simple sentence -- like "Jim is cold" -- incorporates subject, action and complete thought. In this sentence:
Sentences with these three components are called independent clauses. Independent clauses can stand on their own - they form their own sentences. If a sentence is lacking in one of the three components, it is called a dependent clause. Dependent clauses can't stand alone; they need to be joined to another clause.
For more help differentiating between the two, try our article comparing independent and dependent clauses.
Independent and dependent clauses can be joined together to create compound sentences. A run-on sentence has two or more clauses which are joined improperly. To avoid run-on sentences, compound sentences come with rules:
Run-on sentences come in many different varieties. Here are three of the most common types:
A comma splice happens when a comma, rather than a semicolon, has been used to join independent clauses.
A fused sentence mashes two main clauses together with no punctuation at all.
Polysyndeton refers to the use of more conjunctions than a sentence requires.
Here follow examples of each type of run-on sentence described above, with explanations for how to fix them.
Kelly likes to cook, she makes chicken every day.
This is a classic comma splice. "Kelly likes to cook" is an independent clause that can stand by itself. "She makes chicken every day" is also an independent clause that could stand by itself. Joining these two clauses calls for a semicolon, not a comma:
Kelly likes to cook; she makes chicken every day.
Mary likes dogs she has a beagle.
This exemplifies a fused sentence: two independent clauses written together without any punctuation or conjunction to separate them. All that's necessary to fix this sentence is to insert the proper punctuation. Both of the following are valid ways of rewriting the same sentence.
Mary likes dogs; she has a beagle.
Mary likes dogs. She has a beagle.
We went to the park and we ate dinner and we got ice cream and when it got dark we chased fireflies.
This is polysyndeton: the use of excessive conjunctions to extend the length of the sentence. In this case, the word "and" is overused. Sometimes, the overuse of conjunctions like "and" is a deliberate rhetorical choice. Most of the time, however, it's a simple error with an even simpler fix: divide the statement into separate sentences with a bit of punctuation:
We went to the park. Then, we ate dinner and got ice cream. When it got dark, we chased fireflies.
Run-on sentences are easy mistakes. Run-on sentences appear in all sorts of writing, especially in first drafts and time-sensitive writing. As long as you keep to the advice above, however, you should be golden.
If you'd like to read more about the most common kind of run-on sentence, have a look at these examples of comma splices. Happy editing!