This document discusses adjective clauses, which provide additional information about nouns. It notes that adjective clauses use relative pronouns like who, that, which to begin the clause. Adjective clauses can identify specific nouns or indefinite pronouns. The verb in the adjective clause agrees with the number of the noun it refers to. There are two types of adjective clauses - identifying and nonidentifying. Identifying clauses are essential to identify the noun, while nonidentifying clauses provide extra information and are set off with commas.