heavy metal bands like queensryche and fates warning were incorporating unusual elements to their music since the 80s. but in the early 90s dream theater are defining this sound decisively. progressive metal is a broad fusion music genre melding heavy metal and progressive rock. the music typically showcases the extreme technical proficiency of the performers and usually uses unorthodox harmonies as well as complex rhythms with frequent meter changes and intense syncopation.

• seminal progressive metal bands:

dream theater, fates warning

• important progressive metal album:

dream theater - images and words (1992)