To describe the music of Led Zeppelin is a lot like trying to convey to a blind man what Picasso was trying to do with his painting, Les demoiselles d'Avignon. The best way to experience Led Zepp is, possibly, with a great audio player in a dark room, Robert Plant's voice and Jimmy Page's guitar doing all the explaining.
There are the mundane facts, of course. Formed in 1968, this English rock band comprised Jimmy Page, Robert Plant, John Paul Jones and John Bonham. They were supposedly a rock band, but managed to sound heavier, reintroduced the blues to their audience, dabbled in rockabilly and reggae, and even turned to the East in a quest for new sounds.
The experimentation worked well enough to propel Led Zepp to the top of VH1's 100 Greatest Artists of Hard Rock when the dust had settled. They sold over 300 million albums worldwide along the way, and are still the only band to have had all albums reach the US Billboard Top 10.
In the picture: In Los Angeles for a promo (1973).