A pronoun can appear in one of three cases: subjective, in which the pronoun functions as a subject; objective, in which the pronoun functions as an object; and possessive, in which the pronoun functions as a possessor.
Definition
Nouns and pronouns take a certain case depending on their function in a sentence.
Types of pronouns
English pronouns have three kinds of cases: subjective, objective, and possessive.
Subjective Pronouns
A subjective pronoun is a pronoun that refers to the person speaking or writing. In other words, it is a pronoun that represents the point of view of the person who is speaking or writing. The most common subjective pronouns are I, me, we, and us.
Objective pronouns-
You (singular), him/her/it, us, you (plural), them and whom are all objective (or accusative) pronouns. When something is being done to some other object or individual then this case is used.
Possessive pronouns
Possessive pronouns are a type of pronoun that show ownership or possession. They can be used to show ownership of objects, people, or ideas. Possessive pronouns are made up of two parts: the possessive adjective and the pronoun. Possessive pronouns can be used in a variety of ways. They can be used as the subject of a sentence, the object of a sentence, or as an adjective. Possessive pronouns can also be used to join two nouns together.
The singular possessive pronoun "my" can be used as the subject of a sentence:
My favorite color is blue.
The plural possessive pronoun "our" can be used as the object of a sentence:
We went to our friend's house.
The possessive reflexive pronoun "mine" can be used as an adjective:
My – Used to indicate that something belongs to the speaker
Your – Used to indicate that something belongs to the person being spoken to
His – Used to indicate that something belongs to a male
Her – Used to indicate that something belongs to a female
Its – Used to indicate that something belongs to an animal or object
Our – Used to indicate that something belongs to the speaker and one or more other people
Their – Used to indicate that something belongs to a group of people
Conclusion-
Case of pronouns depends on their particular function. They vary with each sentence type.