Many sentences consist of more than one clause.
Clauses are joined together by conjunctions. The conjunction used to join the clauses must be selected for appropriate meaning. If the conjunction is at the beginning of the sentence, a comma will be placed at the end of the first clause in the middle of the sentence. If the conjunction is a fancy conjunction, like those you looked up in the dictionary, a semicolon is used before the conjunction, and a comma is used after the fancy word. To see how conjunctions tie two clauses together, circle the subjects and verbs in each clause and underline the conjunction.