Kill 'Em All features intricate riffing reminiscent of the NWOBHM bands played at high velocity. The album is considered crucial in thrash metal's genesis because it introduced fast percussion, low-register chords, and shredding leads to the genre. Hammett played some pentatonic patterns in addition to his breakneck solos. Ulrich adopted a double time snare pattern that would become a mainstay on Metallica's subsequent albums. Hetfield's vocals evolved from the melodic wail on No Life 'til Leather to a rough-edged bark, and the entire band played faster and more accurately on Kill 'Em All. Author Joel McIver described Burton's and Hetfield's performances as nearly virtuosic, highlighting Burton's smooth-sounding bass and Hetfield's precise picking skills. According to journalist Chuck Eddy, the juvenile lyrical approach to topics such as warfare, violence and life on the road gives the album a "naive charm". The musical approach on Kill 'Em All was in contrast to the glam metal bands who dominated the charts in the early 1980s. Because of its rebellious nature and Metallica's street appearance, it appealed to fans who were not into the mainstream of hard rock.
"Jump in the Fire" was the first song ever written by Mustaine, with lyrics about teenage sexual experience. Hetfield's revised lyrics for the album were written from Satan's point of view, describing how the devil watches people killing each other, and is sure they will go to hell for their actions. "Jump in the Fire" was released as a single in the UK in February 1984 to promote a UK tour with Venom. The single featured "Phantom Lord" and "Seek & Destroy" as live tracks, although they are actually studio recordings with fake crowd noise dubbed over them. The single's cover art features an oil painting titled The Devils of D-Day, created by artist Les Edwards in 1978. 781b155fdc