This document defines and describes different types of sentences. It explains that a sentence is a group of words that makes complete sense, starting with a capital letter and ending with a punctuation mark. Every sentence has two parts - a subject and a predicate. There are four kinds of sentences: assertive sentences that state something and end with a period, interrogative sentences that ask questions and end with a question mark, imperative sentences that give orders/requests and end with a period, and exclamatory sentences that express strong feelings and end with an exclamation point.