This document discusses adjective clauses, also known as relative clauses. It defines relative pronouns such as who, whom, whose, which, that, when and where and provides examples of how each is used in restrictive and non-restrictive clauses. The document also compares restrictive and non-restrictive clauses and provides examples to illustrate the correct use of commas with each. It concludes by listing references and additional online resources for learning more about relative clauses.