It's impossible to imagine what music would be like today if Madonna had never been born. Aside from dominating trends on the charts for a solid twenty years, Madonna changed the way stars approach their own fame.
No one else has changed public personas and musical styles so often without ever losing control of their image (speaking of her image, check out this gallery of her ever-changing looks over the years). And dare we say "Into the Groove" is the greatest dance song ever?
So to celebrate Madonna turning 55, here are 55 of her best tracks, from 1983's "Lucky Star" to a duet she sang with M.I.A. called, appropriately enough, "B-Day Song."