A complete sentence expresses a complete thought. It must have a subject, a verb, and proper punctuation. The subject is the person or thing doing the action. The verb is the action word.
A simple sentence expresses one thought.
A compound sentence contains two simple sentences. Each expresses a complete thought. They are joined by a comma and conjunction (such as and, but , or so) or a semicolon (;).
In a complex sentence, one part of the sentence can stand alone, but the other part cannot.
This sentence is made up of two parts, separated by a comma. Each part has a subject and a verb. However, the words before the comma do not make sense without the rest of the sentence. These words form a dependent clause. A complex sentence has at least one dependent clause. These clauses begin with words such as after, although, because, if, since, when, and while. The words after the comma can stand alone as a sentence. They form an independent clause.