A clause can be either independent or dependent.
* Independent clause: This is a complete thought that can stand alone as a sentence. It has a subject and a verb and expresses a complete idea.
* Example: The cat sat on the mat.
* Dependent clause: This is not a complete thought and cannot stand alone as a sentence. It depends on an independent clause to make sense. It also has a subject and a verb, but it doesn't express a complete idea.
* Example: Because the cat sat on the mat.
A sentence is a group of words that expresses a complete thought. It must contain at least one independent clause.
* Example: The cat sat on the mat, and it purred contentedly. (This sentence contains two independent clauses.)