A pronoun is a word used in place of a noun or another pronoun. There are several types of pronouns: personal pronouns refer to specific persons or things, reflexive pronouns end in "-self" or "-selves" and refer back to the subject, and indefinite pronouns do not refer to specific persons or things. Other pronoun types are demonstrative pronouns which single out nouns, interrogative pronouns used to ask questions, and possessive pronouns which show ownership without apostrophes.