What is Progressive Metal or Prog-Metal?

The clamorous progeny of progressive rock, characterized by the use of complex themes and distorted, non-rhythmic time signatures. Band which typically figure in this category include Dream Theater, Tool, Liquid Tension Experiment, Queensryche and Savatage. These bands create tunes inspired by Progressive Rock giants like Pink Floyd and Rush and amalgamate the tunes with influences from Megadeth, Metallica, Black Sabbath and Iron Maiden.
A few classic Prog-Metal albums are:
· Dream Theater’s A Change of Seasons
· Dream Theater’s Scenes from a Memory
· Liquid Tension Experiment’s Liquid Tension Experiment 1
· Savatage’s Gutter Ballet
· Shadow Gallery’s Tyranny
· Queensryche’s Operation Mindcrime
· Tool’s Lateralus