Heavy metal is a music genre that emerged in the late 1960s and early 1970s, primarily in the United Kingdom and the United States. It is characterized by its loud, distorted guitar riffs, fast and complex drumming, and often aggressive vocals. Heavy metal is generally considered a subgenre of rock music, and it has a wide range of styles and subgenres, including thrash metal, death metal, power metal, and black metal, among others. Some of the most famous heavy metal bands include Metallica, Black Sabbath, Iron Maiden, and Judas Priest.