Apple announced the Apple Music Store—that's the iTunes Store today—on April 28th, 2003. That means on Sunday, April 28th, 2013, the iTunes Store will be 10 years old, and Apple is marking the event with a timeline appropriately called "A Decade of iTunes."
A Decade of iTunes
As shown in the image above, the timeline has milestone events in the history of iTunes. In 2003, for instance, Apple proudly announced on September 8th that 10 million songs had been downloaded. On February 6th of 2013, Apple announced the 25 billionth download. Zoinks!
The timeline also includes the launch of international stores, the addition of services such as videos and the launch of the App Store, the addition of The Beatles catalog, and much more. You can find it in the banners atop the iTunes Store's main page.