Metallica is the self-titled fifth studio album by the American metal band Metallica, originally released in 1991 and widely known as the "Black Album". Under producer Bob Rock the band opted for shorter, more direct songs and a tighter, heavier sound than on their earlier thrash albums. The album produced some of the best-known songs of their career, including "Enter Sandman", "The Unforgiven", "Nothing Else Matters", "Sad But True" and "Wherever I May Roam". The album reached number one on the US album chart and became one of the best-selling rock albums of all time.