This document discusses adjective clauses, also known as relative clauses. It explains that adjective clauses provide extra information about nouns and function like adjectives. There are two types of adjective clauses: subject clauses and object clauses. Subject clauses have the same subject as the main clause, while object clauses have a different subject than the main clause. Relative pronouns like who, whom, whose, which, and that are used to connect the adjective clause to the main clause by substituting for the original noun. Examples of both subject and object clauses are provided.