Run-on sentences are among the most common sentence-level errors. Although many people think of run-ons as sentences that are just "too long," the problem has little to do with sentence length.
Simply put, run-on sentences are created when two (or more) independent clauses are improperly joined. (An independent clause is a clause that contains a subject and a verb and can stand alone as a complete sentence.)
In a run-on, independent clauses may be run together, with no punctuation or transitional words between them:
The attorney encouraged her client to settle the case out of court the client refused because he wanted to go to trial.
Or they may be insufficiently connected with just a comma:
The lawyer handed the judge a memo, it fell on the floor.
(This type of run-on is often called a comma splice.)
Once you've identified them, run-ons can be easily corrected in several ways:
- Make the run-on two separate sentences. This is often the best choice when the original sentence is very long.
The attorney encouraged her client to settle the case out of court. The client refused because he wanted to go to trial.
- Use a semicolon, or a semicolon plus a transitional word, to link the clauses.
The lawyer handed the judge a memo; however, it fell on the floor.
- Use a conjunction (and a comma) to join the clauses:
The lawyer handed the judge a memo, but it fell on the floor.
- Reword the sentence to turn one of the independent clauses into a dependent clause using a subordinating conjunction.
When the lawyer handed the judge a memo, it fell on the floor.
Examples of common subordinating conjunctions are when, because, before, after, whereas, while, and unless.