Metallica's 1991 album Metallica was the band's first album to debut at number one on the US Billboard 200.
The Billboard 200 ranks albums and extended releases in the United States, unlike the Billboard Hot 100, which ranks individual songs. Metallica's debut at number one therefore measured the album's first-week popularity rather than the performance of a single track.
The album opened with 598,000 copies sold in its first week and remained at the chart's summit for four consecutive weeks. Its success was especially significant because the band had previously built its reputation through heavy touring and a devoted metal audience rather than mainstream pop exposure.
The achievement is sometimes mixed up with the album's singles, including “Enter Sandman,” which charted on the Billboard Hot 100. Those are separate chart records. The album's historic debut belongs to the Billboard 200, the principal US album chart.