The document discusses the four types of sentence structures: simple, compound, complex, and compound-complex. It provides examples and definitions of each type. A simple sentence contains one independent clause. A compound sentence contains two independent clauses joined with a conjunction. A complex sentence contains one independent clause and one or more dependent clauses. A compound-complex sentence contains two or more independent clauses and one or more dependent clauses. The document concludes with a practice quiz to test identification of these sentence structures.