Вот здесь почитайтеhttps://ru.wikipedia.org/wiki/%D0%A2%D1%8F%D0%B6%D1%91%D0%BB%D1%8B%D0%B9_%D0%BE%D1%81%D1%82%D1%80%D1%8B%D0%B9_%D1%80%D0%B5%D1%81%D0%BF%D0%B8%D1%80%D0%B0%D1%82%D0%BE%D1%80%D0%BD%D1%8B%D0%B9_%D1%81%D0%B8%D0%BD%D0%B4%D1%80%D0%BE%D0%BC