[OkayPhysicist]

Yeah, exactly. Commonly, the salts are stored right next to the hashes in the DB, because they serve their purpose even if the attacker knows what the salts are. By using a different salt for every password, the attacker needs execute a full "guess, hash, compare, repeat" attack on each user, as opposed to "guess, hash, compare against all user passwords, repeat" on the entire database.