Metal music was born out of progressive rock in the sixties and got longer, harder, and faster. Heavy metal made its way onto FM radio in the seventies and carved a niche of its own. The genre exploded in the 80's due to MTV, and wider mainstream exposure courtesy of some melodic glam metal acts that began to break into the top 40. Sub genres include death metal, gothic metal, thrash metal, speed metal, rap metal, and metalcore, to name a few. Themes in metal tend to include angst, mythology, and apocalyptic elements. Long hair and black leather are staples in metal fashion. Metal maintains a healthy following around the globe, and many european acts have become quite popular in the US. Internet radio service RadioIO offers it's unique metal channel Metallurgy. Hosted by David Sterling, Metallurgy boasts a wide variety of metal from the tradition tracks of the 70's right up to the favorites of today.