Изучайте https://ru.m.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B8%D1%81%D0%BE%D0%BA_%D0%B2%D0%BE%D0%B9%D0%BD_%D0%B8_%D0%B2%D0%BE%D0%BE%D1%80%D1%83%D0%B6%D1%91%D0%BD%D0%BD%D1%8B%D1%85_%D0%BA%D0%BE%D0%BD%D1%84%D0%BB%D0%B8%D0%BA%D1%82%D0%BE%D0%B2_%D0%A0%D0%BE%D1%81%D1%81%D0%B8%D0%B8