Subject Pronouns and Object Pronouns
The subject in a sentence is the entity (person, thing, object or place) that is doing something. When a pronoun (I, You, He/She/It, We, You, They) takes the place of a subject in a sentence, it becomes a subject pronoun.
The object in a sentence is the entity (person, thing, object or place) that is being acted upon. If the object is a person, we use object pronouns.
I (subject) am driving a car (object).
I (subject) am calling him (object pronoun).
We (subject) are going to see them (object pronoun).
She (subject) will message you (object pronoun).
A possessive pronoun is used to express ownership. They are not immediately followed by a noun, but they stand alone.
The red car is mine.
The strawberry ice cream is hers, the chocolate one is yours.
The book is his.
When a possessive pronoun is immediately followed by a noun, it becomes a possessive adjective. Possessive adjectives do not stand alone.
I am driving my car, you are riding your bike.
She is reading her book.
We are bringing our dogs to the BBQ, are you bringing yours (possessive pronoun)?
Are their children in High School?
When the subject and the object are the same person, we use reflexive pronouns.
I (subject) can see myself (object pronoun, same as subject = reflexive pronoun) in the mirror.
She can take care of herself. (Note: The sentence “She can take care of her” would be grammatically correct, but would have a different meaning. “her” in this case would signify a different person!)
We need to bring food ourselves.
They did this themselves.