Quackery, often synonymous with health fraud, is the promotion of fraudulent or ignorant medical practices. A quack is a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or publicly, to have skill, knowledge, qualification or credentials they do not possess; a charlatan or snake oil salesman". The term quack is a clipped form of the archaic term quacksalver, derived from Dutch: kwakzalver a "hawker of salve" or rather somebody who boasted about their ‘salves’, more commonly known as ointments. In the Middle Ages the term quack meant "shouting". The quacksalvers sold their wares at markets by shouting to gain attention.