Personal pronouns refer to people or things and can be subject pronouns like "I" or object pronouns like "me". Pronouns must agree with their antecedents in number and gender and refer clearly to the intended noun. There are also possessive pronouns like "his" and "hers", indefinite pronouns like "anyone", reflexive pronouns like "myself", and intensive pronouns like "himself" that add emphasis. Proper use of pronouns is important for clarity and avoiding ambiguity.