The relative pronouns are who, whom, whose, and that. We sometimes use when, what, where and why as relative pronouns.
There is a commonly-held belief that whose can only be applied to people, not to things. This is not so, however, and in the words of the immortal H. W. Fowler: “Let us, in the name of common sense, prohibit the prohibition of whose inanimate; good writing is surely difficult enough without the forbidding of things that have historical grammar, and present intelligibility, and obvious convenience, on their side”. Modern English Usage (1926)