Speed metal is an extreme 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. It is usually considered less abrasive and more melodic than thrash metal. However, speed metal is usually faster and more aggressive than traditional heavy metal, also showing more inclination to virtuoso soloing and featuring short instrumental passages between couplets. Speed metal songs frequently make use of highly expressive vocals, but are usually less likely to employ "harsh" vocals than thrash metal songs. Wikipedia