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.