Progressive Metal

Progressive Metal is a subgenre of progressive rock as much as it is a subgenre of heavy metal, and this is how its sound is defined: a blend of heavy, guitar-oriented metal music enriched with compositional innovation and complex arrangements, usually expressed through diverse instrumentation and often (but not always) with odd-time signatures. Common, but not essential to define the movement, are the frequent use of keyboards, high-pitched vocals, concept lyrical themes and tracks of longer duration. Read more here.