An ELT Glossary : Simple sentences, compound sentences, complex sentences, and compound-complex sentences

A simple sentence consists of one main clause. Examples : 
John lives in Brighton.

A compound sentence consists of two or more main clauses linked by a co-ordinating conjunction (and, but, or). Examples :  
John lives in Brighton but he works in London. 
John lives in Brighton but he works in London and so he has to commute each day.

A complex sentence consists of a main clause and at least one subordinate clause. Examples :
Although he works in London, John lives in Brighton.
Although he works in London, John lives in Brighton where he has a lovely house by the beach.

A compound- complex sentence has at least two co-ordinated main clauses, plus at least one subordinate clause. Examples :
John works in London, but he lives in Brighton where he has a lovely house by the beach.



Probably the best grammar of English ever published....

Quirk, Greenbaum, Leech and Svartvik (1972), A Grammar of Contemporary English, Longman