Pronouns are words that stand for and take the place of nouns.
Compound pronouns: How to tell whether to write "he and I" or "he and me."
Who or whom: How to tell whether to write "to who I was speaking" or "to whom I was speaking."
That or which: How to tell whether to write "the sweater that I wore" or "the sweater which I wore."
Whose or of-which: How to tell whether to write "the car whose tires are bald" or "the car of which the tires are bald."
It's or its: How to tell whether to write "the cat ate its dinner" or "the cat ate it's dinner."
You or yourself: How to tell whether to write "a person like you" or "a person like yourself."
Pronouns in comparisons: How to tell whether to write "she likes him as much as I" or "she likes him as much as me."

Pronouns following 'to be': How to tell whether to write "It was I who called" or "It was me who called."
Plural pronouns: Pronouns that stand for multiple things.
Pronoun gender: Pronouns that stand for male or female people.