Alright let's do this shit.
Progressive Rock? What the shit is that?
Progressive rock is an ambitous sub-genre of rock music originating from Britain that fuses rock music with folk, jazz, classical, and pretty much everything else you can think of. It is famous for having lengthy song structures (up to 77 minutes in one case), concept albums, eloquent lyrics, and huge instrumental jams. It spawned from many musicians feeling the need to burst from the bluesy image that rock had at the time, and fuse it with many other styles, particularly eastern.
Basically, it looks at standard rock, says "bugger that lol" and then fills a song with flute solos.
Where did it come about?
Britain, mostly. The Beatles are often regarded as the catalyst, mostly due to their efforts with avant garde and eastern music. But the first true progressive rock album was from King Crimson, who somehow managed to write a jazz-metal song in the 60s. It was also fucking amazing:
Another media of which prog spawned from was the psychadelic scene, in fact, the two biggest progressive bands of the 70s, Geneis and Yes, started life out as psychadelic bands, and then there's Pink Floyd, who are, in a word, massive. Literally, one of their albums stuck on the Top 100 charts for about ten years, if I remember correctly.
Alright, so what can I expect from prog rock?
There are a shit ton of sub-genres, seriously [Click me!], but I may aswell try to sort all the main ones.
Here's the arguably most popular one, Yes, Genesis, Camel, the latter half of Pink Floyd's career and so on. It can be catagorised by lush keyboards, lengthy song structure, and lots of input from classical music.
That guitar solo!
Hard rock with a dash of intelligence and time siggys. Lots of heavy metal artists, such as Iron Maiden, take great inspiration from this sort of music.
Awesome shit, manages to blend and mash together styles flawlessly, a song might start symphonic and downbeat and end as a fast pased jazz fusion jam. Listening to an eclectic band such as King Crimson or Van Der Graaf Generator is unpredictable, you'll never know what to expect.
:350: Trippy shit. Takes influence from eastern music, avant-garde and such.
Metal + prog, what's not to get? It also sounds rad as hell, yo.
There's more stuff click this handy banner to go to pretty much the biggest Prog Rock forum out there.
If you like this stuff then go find the post-rock thread wherever it went.
Also for funnies: http://www.cracked.com/funny-2359-progressive-rock/