How many copies have Metallica album "Metallica" (A.K.A The Black Album) sold worldwide (in Millions of Copies)?

Metallica's self-titled album, also known as "The Black Album," has sold over 20.5 million copies worldwide. Released in 1991, the album was a commercial success and solidified Metallica's status as one of the biggest bands in the world. The album featured hits such as "Enter Sandman" and "Nothing Else Matters," which helped propel its sales to over 20.5 million copies, making it one of the best-selling albums of all time.