Heavy metal is a genre of rock music that emerged as a defined musical style in the 1970s, having its roots in hard rock bands which, between 1967 and 1974, mixed blues and rock to create a hybrid with a thick, heavy, guitar-and-drums-centered sound, characterised by the use of highly-amplified distortion. Out of heavy metal various subgenres later evolved, many of which are referred to simply as "metal". As a result, "heavy metal" now has two distinct meanings: either the genre as a whole or what is known as "classic rock" in the 1970s style, as exemplified by Deep Purple, Led Zeppelin  and Black Sabbath.

Heavy metal began gaining popularity in the 1970's and '80s, at which time many of the now existing subgenres first evolved. Heavy metal has a large world-wide following of fans known by terms such as "metalheads" and "headbangers".