What are the differences among types of sentences, i.e., simple, compound, complex, and compound-complex

Sentences can be classified two different ways. Sentences have a function -making a statement, asking a question, giving a command, uttering an exclamation, etc. Sentences also have a structure, with the four basic structures being: simple, compound, complex, and compound-complex. A simple sentence consists of a single main clause and no subordinate clause, e.g., Last winter was unusually snowy. A compound sentence consists of two or more main clauses and no subordinate clause, e.g., Junior year was complicated, but senior year was even more so. In a compound sentence, the clauses may be joined by a coordinating conjunction and a comma, by a semicolon alone, or by a conjunctive adverb and a semicolon. A complex sentence contains one main clause and one or more subordinate clauses, e.g., Rain finally came, although many people had already resorted to watering their lawns. Those that remained were able to protect their houses because the hurricane came and left quickly. A compound-complex sentence has the characteristics of both the compound sentence (two or more main clauses) and the complex sentence (at least one subordinate clause), e.g., Even though government aid finally came, many people had already been reduced to poverty, and others had been forced to move.