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, from Dutch: kwakzalver a "hawker of salve". In the Middle Ages the term quack meant "shouting". The quacksalvers sold their wares on the market shouting in a loud voice.