Speed metal is a subgenre of heavy metal music that originated in the late 1970s from new wave of British heavy metal (NWOBHM) roots. It is described by AllMusic as "extremely fast, abrasive, and technically demanding" music.
Motörhead playing in 2005
Thrash metal is an extreme subgenre of heavy metal music characterized by its overall aggression and fast tempo. The songs usually use fast percussive beats and low-register guitar riffs, overlaid with shredding-style lead guitar work.
Kirk Hammett and James Hetfield of Metallica (pictured in 2008). Metallica's early work is regarded as essential to the development of the genre in the 1980s.
New York band Anthrax was among the earliest and most successful thrash acts.
Venom's early work is considered a major influence on thrash metal.
Slayer (pictured in 2007) released Reign in Blood in 1986, considered a landmark achievement in the genre's history.