Judas Priest is an immensely influential heavy metal band formed in 1969 in Birmingham, England by K.K. Downing and Ian Hill. The band"s classic line-up consists of vocalist Rob Halford, guitarists K.K. Downing and Glenn Tipton, and bassist Ian Hill. They epitomize the classic heavy metal genre, particularly the NWOBHM ("New Wave of British Heavy Metal") movement, and have influenced hundreds of musicians and bands. Their popularity and influence earned them the nickname "The Metal Gods". Musical style and influences One of the progenitors of heavy metal, Judas Priest are best known for their twin-lead-guitar sound and the complex guitar duets of K.K. Downing and Glenn Tipton; and for Rob Halford"s high-pitched screams, and lead vocals. However, the band"s biggest musical innovation is the dual "rhythm guitar", i.e. the accompaniment, or riff, which plays an essential role in all hard rock genres and especially in heavy metal. Although Wishbone Ash and the Scorpions have had two guitarists each and to some extent did play harmonies and dual leads prior to Judas Priest, none had played dual rhythm consistently as an integral part of their music. Dual rhythm consists of two guitarists playing the same exact melody (riff) simultaneously, often on the same exact octave, which is slightly different from traditional harmonies. There may be minor differences in sound, tone, tenacity, and an occasional deviation from the melody for a very short period (like a short improvisation, or insert - just a few notes). Since Judas Priest introduced this new style of rhythm guitar with their first release Rocka Rolla, it has become a standard feature of heavy metal. Another important aspect of their style is inserting very melodic solos, or "lead breaks" - between fast riffs (e.g. "The Sentinel", "Electric Eye", "Night Crawler", "Hellrider"). Many people, including influential musicians and members of prominent hard rock and heavy metal bands, believe that the foundation for what would define "pure" heavy metal were three early Judas Priest albums; Sad Wings of Destiny (1976), Sin After Sin (1977), and Stained Class (1978).