Like so many artistic creations, the concept album is not precisely defined. In a vague sense, its any record where all the songs contain linked musical or lyrical ideas, sometimes telling a story and even occasionally featuring a protagonist like The Whos Tommy yet other times itll just be a loose theme that is explored across the albums tracks. Any genre can produce a concept album. Progressive rock is well-known for it, but concept albums exist in country, jazz, pop and, indeed, across the whole musical landscape. It's seen a resurgence recently: in 2004, Green Day brought the concept album to a new generation and a new audience with American Idiot, an MTV-ready album that loudly proclaimed the bands politics and spawned multiple hits, and rap group Insane Clown Posse have nearly formed a cult around their albums prophesying a demented clown carnival. There are thousands of albums that could fit the criteria, and therefore a list like this can only try to represent the concept album in as many ways as possible from instrumental experiments to lyrical novellas and expositions of personal philosophy. They arent explicitly ranked by quality each is approximately as worthy as the others but like so many good concepts, the journey there is as much of the fun as the destination.