Trolls are mythical creatures in Scandinavian folklore, living in mountains or forests. Usually large and strong with hair covered bodies and green or gray skin, they were vulnerable to sunlight. They were afraid of fire and iron, and some could smell the scent of distant humans. They had magical powers such as shapeshifting, controlling the elements or casting spells of invisibility. Some were depicted as being mischievous and some were seen as evil. Today 'troll' describes people who post hurtful and hateful comments online, hiding behind anonymity.