Simple sentence - is one independent clause
Example: Sally walks her dog every day.
Compound Sentence - two independent clauses separated by a coordinating conjunction.
Example: Larry loves to fish and Ben loves to go hiking.
Coordinating Conjunctions: FANBOYS (For, And, Nor, But, Or, Yet, So)
Complex Sentence - An independent and a dependent clause separated by a subordinating conjunction.
Example: Each of the students was working on his writing assignment when the bell rang
(subordinating conjunction is in the middle of the sentence. No comma needed)
Example: When the bell rang, the students were working on their writing assignment.
(subordinating conjunction at the beginning of the sentence. A comma is needed)
Compound-Complex Sentence - two independent causes and one or more dependent clauses.
Example: I have never been a great student, but because I like grammar, I have spend a lot of time studying sentence structure.
(a comma is needed to separate the dependent clause from the two independent clauses. )
Example: Since Micheal Jordan was cut from his high school basketball team, many thought he would quit, but he didn't give up.