Comma Splices and Run-On Sentences

A Comma Splice is two sentences incorrectly joined with a comma.
A Run-On Sentence is two sentences joined without punctuation.

There are four acceptable ways to fix comma splice and run-on errors:

1. Join the two independent clauses with a semicolon (;).

Mary is studying for final exams; that is why she has not written.

2. Make each independent clause a separate sentence by using end punctuation (a period, question mark, or exclamation point).

Mary is studying for final exams. That is why she has not written.

3. Make one of the independent clauses a dependent clause.

Since Mary is studying for final exams, that is why she has not written.

4. Connect the two independent clauses with a comma plus a coordinating conjunction (and, but, for, so, or, yet).

Mary is studying for final exams, and that is why she has not written.