The New Wave of British Heavy Metal (frequently abbreviated as NWOBHM) is a heavy metal music movement that started in the late 1970s, in Britain, and achieved some international attention by the early 1980s. The era developed as a reaction in part to the decline of early heavy metal bands such as Deep Purple, Led Zeppelin and Black Sabbath. NWOBHM bands toned down the blues influences of earlier acts, increased the tempo, and adopted a "tougher" sound, taking a harder approach to its music. It was a scene directed almost exclusively at heavy metal fans. The era is considered to be a main foundation for heavy metal sub-genres with acts such as Metallica citing NWOBHM bands like Saxon, Diamond Head and Motörhead as a major influence on their musical style. Speed metal is a sub-genre of heavy metal music originating in the early 1980s, rooted in the NWOBHM and hardcore punk. It is described by the Allmusic site as "extremely fast, abrasive, and technically demanding" music. Also according to Allmusic, speed metal eventually toned down its intense tempos and evolved into thrash metal *Source : Wikipedia More Details : http://en.wikipedia.org/wiki/New_Wave_of_British_Heavy_Metal http://en.wikipedia.org/wiki/Speed_metal