Who is used for humans and domestic animals.
*Domestic animals are animals humans use for pets. (Ex: dogs, cats, birds, etc)
My friend, who is the nicest person in the world, gave me a great birthday present.
(who = my friend)
||Whom is used for humans.
||Dr. Crew, whom Ben doesn't like, is my professor in psychology.
(whom = Dr. Crew)
||Which is used for things and animals.
||Seth has a book which has great pictures. (which = book)
||That is used for humans, animals, or things.
||John is writing a paper that his professor assigned. (that = paper)
||Where is used to represent a location.
||The apartment where I live, is in a good location. (where = apartment)
||When is used to represent a specific time.
||That time when I broke my arm was horrible. (when = time)
||Whose is used to show ownership.
||I know the girl whose essay won an award. (whose = girl)