Grammatically, sentences may be classified as simple, compound, complex, and compound-complex.
Simple sentences
A simple sentence consists of one independent clause and no dependent clause.
Compound sentences
A compound sentence consists of two or more independent clauses and no dependent clause. The clauses may be joined by a comma and a coordinating conjunction (and, but, or, nor, for, so, yet) or by a semicolon.
Complex sentences
A complex sentence consists of one independent clause and at least one dependent clause.
Compound-complex sentences
A compound-complex sentence consists of two or more independent clauses and at least one dependent clause.