15 Mini-Grammar Review: Fragments, Run-ons, and Comma Splices

The most common sentence errors have one thing in common:¬†they are mistakes about sentence boundaries and what punctuation to use. It’s important to understand how to write complete sentences and fix errors related to making complete sentences (fragments, comma splices, run-on sentences).

Independent Clause: An independent clause is a unit of meaning with a subject and a verb that can be punctuated as a complete sentence. Native speakers of English will usually recognize an independent clause by itself as a complete sentence.

A complete sentence must meet five simple criteria:

  • It must have a subject.
  • It must have a verb.
  • It must begin with a capital letter.
  • It must end with a period, question mark, or exclamation mark.
  • It must make sense in English.

A comma splice, fragment, and run on do not meet the criteria for a complete, correct sentence.

A fragment is an incomplete sentence. A fragment will be missing a subject or a verb or both. Please watch this video from Kahn Academy:

A run-on sentence is two independent clauses joined with no intervening punctuation (i.e., run together). A run-on sentence has too many subjects and verbs!

A comma splice is two independent clauses (complete sentences) joined with a comma. A comma splice is basically a run-on sentence that has a comma between each sentence.

Here’s another video from Kahn Academy that explains how to recognize run-ons and comma splices:

Content adapted from “Tips for Writing Complete Sentences” in The Word on College Reading and Writing by Babin, et al licensed by CC NC 4.0.