A pronoun is a category of words in a language that replace or represent in a generic way a more specific noun, which is a person, place or thing. Pronouns fall into a number of subcategories, including subjunctive personal pronouns, objective personal pronouns and possessive pronouns.
Subjunctive personal pronouns replace the subject of a sentence, as in, "I went to the store." Objective personal pronouns are used as the direct object, indirect object or object of a preposition. Examples include, "John throws it" and "John rode with them." Possessive pronouns are used to show ownership, as in, "The car is mine."