Metallica is an American heavy metal band formed in Los Angeles in 1981, later based in the San Francisco Bay Area. They are associated with thrash metal and heavy metal, noted for blending fast tempos, aggressive guitar riffing, and complex song structures with melodic elements. Over several decades they gained prominence through a series of studio albums and extensive touring, influencing both underground and mainstream metal scenes. Their music often features downpicked, palm-muted guitar work, virtuosic lead playing, driving rhythm sections, and varied arrangements ranging from short, hard-hitting tracks to longer, more intricate compositions.