case
The form a pronoun takes because of its job in a sentence: subject, object or possessive.
subject pronoun
Does the action: I, you, he, she, it, we, they, who.
object pronoun
Receives the action or follows a preposition: me, you, him, her, it, us, them, whom.
possessive pronoun
Shows ownership, with no apostrophe: my/mine, your/yours, his, her/hers, its, our/ours, their/theirs, whose.
reflexive pronoun
Ends in -self or -selves and refers back to the subject: I hurt myself.