In 1999, Billboard Magazine reported that the United States had more
than 500 radio stations that specialized in heavy metal, a number that
had tripled in 10 years. Those radio stations confirmed the recovery of
heavy metal after its decline in the recent decade, which later helped
reunite legendary bands such as Iron Maiden, Judas Priest, and Black
Sabbath. From its origins in hard rock to new bands such as Trash Metal,
heavy metal had marked its own course in the last decade. It obtained
the necessary momentum to achieve a solid cultural and social position
among the general public. Chapters of this music chronicle focus on
progressive, funk, gothic, and groove metal while giving examples and
histories of metal bands within each type.