Metallica is a band from the United States that has been around for over 30 years. They play a type of music called 'heavy metal' which is loud and intense, with screaming vocals and fast-paced guitar riffs. Metallica's most popular songs include "Enter Sandman," "Nothing Else Matters," and "St. Anger." They have been around for a long time and have inspired countless other bands to follow in their footsteps.