why are house elves slaves

House elves are a type of magical being that live in households and serve their owners, known as "masters" or "mistresses." They are considered slaves because they are considered property and are expected to perform household chores and tasks without any compensation or freedom of choice. House elves are treated as inferior to wizards and witches, and they are often abused and mistreated. However, some house elves, such as Dobby, have managed to gain their freedom and become independent.