A sentence fragment is a group of words that does not express a complete thought. It is missing a subject, a verb, or both.

This is a sentence fragment because it does not express a complete thought.

A complete sentence contains at least one independent clause, which has a subject and a verb and expresses a complete thought.

A run-on sentence occurs when two or more independent clauses are joined without appropriate punctuation or conjunctions.

A comma splice is a grammatical error that occurs when two independent clauses are joined by a comma without a coordinating conjunction.

A simple sentence consists of one independent clause and expresses a complete thought.

A compound sentence contains at least two independent clauses joined by a coordinating conjunction or a semicolon.