Apple's first run at a jukebox, which appeared in 2001, was the result of acquiring a company called SoundJam.
The early iteration of iTunes, with its now slightly confusing and broken up interface for browsing music, was hailed at the time for its otherwise simple layout of buttons and virtual knobs, and for its brushed aluminum aesthetic.
But there was something missing...
A few updates later, Apple added all sorts of ways to organize music, including smart playlists.
To solve the issue of where people would actually get music if they weren't just ripping CDs, Apple made its first run at the iTunes Store, unveiling the virtual marketplace in 2003.
The iTunes Store was a big deal because it was directly integrated into Apple's iTunes software, meaning users didn't need to leave the software to hunt down songs.
People snapped up songs. The iTunes Store passed the 500 million milestone in 2005, when Amy Greer of Lafayette, Ind., purchased Faith Hill's "Mississippi Girl" -- and won a golden ticket from Apple: 10 iPods, a gift card for 10,000 songs, and an all-paid trip for four to a concert by Coldplay. Customers of the iTunes Store have since downloaded more than 25 billion tracks.
One of the first big steps in making iPhones and iPods more independent from computers was adding a Wi-Fi iTunes Store right on the devices. Apple has since made the Store work on cellular networks too, letting people download music and apps on the go.
Over the years, Apple has tried all sorts of ways to further integrate the iTunes Store into its iTunes Software. One such effort was a sidebar that would check out what you already had in your iTunes library and offer suggestions for other music you might like (and might purchase by way of the Store).
In successive versions of the iTunes Store, Apple retooled the look and the feel of the interface, but the layout has generally remained the same.
With iTunes 11, Apple made the store almost identical on desktop and mobile devices.