Metalcore is a fusion genre that incorporates elements of heavy metal and hardcore punk. The term is a portmanteau of heavy metal and hardcore punk. Metalcore is typically melodic, emphasizes breakdowns, and sometimes discards the conceptual trappings of both its parent genres. Through the 1990s, metalcore was mostly an underground phenomenon, but from roughly 2004 to the present, many bands have appeared on the Billboard album charts. Due to the rise in popularity in the United States during the early 2000s, the genre has also been described as the "New Wave of American Metal" by some, as an allusion to the New Wave of British Heavy Metal of the late 1970s.