A sentence is a group of words that expresses a complete thought. There a four types of sentences in the English language. They are; imperative, declarative, exclamatory and interogative. Often times, a sentence is made up of one subject and one predicate.
Simple, compound and complex sentences are the three types of sentences according to the structure. A simple sentence consists of a subject and a predicate but a compound sentence consists of two or more subjects and two or more predicates. While the complex sentence can be adjective, noun or adverb clause.