Case refers to the different forms that nouns and pronouns take to deliver information. The case of a noun or a pronoun communicates how that word relates to other words in a sentence. For example, I, me, and mine are three different cases of the singular first-person pronoun. (I wanted a small wedding, but my parents asked me to invite all their friends. Unlike my sister's wedding, mine was quite large.)

                English has three cases: subjective, objective, and possessive.

Personal pronouns are the most common type of pronouns. They have a full range of cases that show changes in person (first, second, and third person) and number (singular and plural).

CASE OF PERSONAL PRONOUNS
 

	Subjective	Objective	Possessive
Person	sing.     plur.	sing.     plur.	sing.                                    plur.
First	I        we	me     us	my/mine
Second	you   you	you   you	your/yours                 your/yours
Third	he     they  she   it	him her it	his                              their/theirs                her/hers its

A pronoun in the subjective case functions as a subject.
            We were going to be married.
                    [We is the subject.]
            John and I wanted an inexpensive band to play at our wedding.
                    [I is part of the compound subject John and I.]
            He and I found a one-person band we could afford.
                    [He and I are compound subjects.]

A pronoun in the objective case functions as a direct object, an indirect object, or the object of a preposition.
            We saw him perform in a public park.
                    [Him is the direct object.]
            We showed him our budget.
                    [Him is the indirect object.]
            He understood and shook hands with me.
                    [Me is the object of the preposition with.]

A pronoun in the possessive case indicates possession or ownership.
            The musician's contract was in the mail the next day.
                    [Musician's, a noun in the possessive case, indicates ownership.]
            Our signatures quickly went on the contract.
                    [Our, a pronoun in the possessive case, indicates possession.]