Thrash metal (or simply thrash) is an extreme subgenre of heavy metal music characterized by its overall aggression and often fast tempo. The songs usually use fast percussive beats and low-register guitar riffs, overlaid with shredding-style lead work. The lyrics often deal with social issues and criticism of The Establishment, using direct and denunciatory language, an approach borrowed from hardcore punk. The genre evolved in the early 1980s from combining the fast drum beats and attitude of hardcore with the double bass drumming and heavy, complex guitar style of the new wave of British heavy metal (NWOBHM). It emerged partially as a reaction to the more conventional and widely acceptable glam metal, a less aggressive, pop music–infused heavy metal subgenre which appeared simultaneously. Thrash metal was an inspiration for subsequent extreme genres such as death metal and black metal.