"Enter Sandman," the iconic lead single from Metallica's 1991 self-titled fifth album, dramatically propelled the band to worldwide fame and sales exceeding 30 million for the record. The powerful main riff was conceived by Kirk Hammett, with James Hetfield crafting the popular lyrics dealing with a child's nightmares. Initially, Hetfield's lyrics were considerably darker, but producer Bob Rock and drummer Lars Ulrich encouraged a revision, establishing the song as the "foundation" for the entire album, even before its final lyrics were set. Its meticulous recording, overseen by Rock, involved groundbreaking techniques like Hetfield's "wall of guitars" and extensive microphone setups to create a massive, live-concert sound. Achieving #16 on the US Billboard Hot 100 and a 9x platinum certification, "Enter Sandman" remains a critically acclaimed staple in Metallica's live performances since its release.