Canadian rock describes a wide and diverse variety of music produced by Canadians, beginning with British and American style rock 'n' roll in the mid-20th century. Since then Canada has had a considerable impact on the development of the modern popular music called rock. Canada has produced many of the genre's most significant groups and performers, while contributing substantively to the development of the most popular subgenres, which include pop rock, progressive rock, country rock, folk rock, hard rock, punk rock, heavy metal and indie rock.