Title: Four Sentence Types
Course: Introduction to Grammar

Experienced writers use a variety of sentences to make their writing interesting and lively. Too many simple sentences, for example, will sound choppy and immature while too many long sentences will be difficult to read and hard to understand. We can categorize sentences into four main types, depending on the number and type of clauses they contain:

Simple (one independent clause):
The answer shocked me.
Compound (more than one independent clause, no dependent clauses):
The answer shocked me, but it was right.
Join the independent clauses with coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so)
Complex (one independent clause and at least one dependent clause):
Although he spoke correctly, I couldn't understand him.
Compound-complex (more than one independent clause and at least one dependent clause):
Although he spoke correctly,
I couldn't understand him for he had a strong accent.

Further explanation is found at this website. Don't forget to quiz yourself at the bottom.