вам сюда http://ru.wikipedia.org/wiki/%D0%A2%D0%BE%D0%BF%D0%BB%D0%B8%D0%B2%D0%BD%D1%8B%D0%B5_%D0%B3%D1%80%D0%B0%D0%BD%D1%83%D0%BB%D1%8B