Simple Sentence: contains only one independent clause.
Compound Sentence: contains two or more independent clauses joined by a coordinating conjunction, semicolon, or a semicolon followed by a conjunctive adverb.
Complex Sentence: contains one independent clause and at least one dependent clause joined by subordinating conjunction, or relative pronoun.
Complex-Compound Sentence: contains at least two independent clauses and one or more dependent clauses. It is also sometimes called compound-complex sentence.