There are two types of clauses: independent clauses and subordinate clauses. Independent clauses can stand alone as a complete sentence while subordinate clauses cannot. Subordinate clauses are used as adjectives, adverbs, or nouns. Adjective clauses modify nouns and begin with relative pronouns like who, whom, whose, which, and that. Adverb clauses modify verbs, adjectives, or other adverbs and begin with subordinating conjunctions like after, because, where, if, that, and than. Noun clauses are used like nouns and begin with that, if, whether or not.