An example of a simple compound sentence is "John wanted to get a hamburger, but Jane wanted to eat at home." Another example is "She smiled at the baby, and he held out his arms for her." A compound sentence is a sentence made up of two or more complete sentences joined together by a conjunction or a semi-colon.
In a simple compound sentence, all clauses are independent, meaning each clause can stand alone as a sentence. In a compound-complex sentence, there are at least two independent clauses and at least one clause that is dependent and, therefore, cannot stand alone.
Often a coordinating conjunction joins the independent clauses in a simple compound sentence. Examples of such conjunctions are "and," "but," "so" and "yet." A comma precedes the coordinating conjunction in compound sentences as in the above examples.
Other times, a conjunctive adverb joins the clauses. "Therefore," "however" and "as a result" are examples. A semi-colon precedes the conjunctive adverb, and a comma follows it. A sentence with this construction is "Bob wanted the red sports car; however, it cost too much."
Alternatively, no conjunction may appear between the two clauses. In this case, a semi-colon separates them. An example of such a sentence is "Bill ordered the steak; Carol opted for chicken."