Simple sentences ... clauses in a compound sentence still make sense on their own and so we use coordinating conjunctions, such as 'and', 'but' and 'so' to link them together. Complex sentences ...

A compound sentence consists of two or more independent clauses (or simple sentences) combined into one sentence. The fox jumped over the dog, and the dog ran under the fence. The dog loves treats; ...

However, there is a danger that the overuse of complex-compound sentences can make essays difficult to read and maybe confusing to the reader. A good writer will use a range of simple, compound, ...