The Apple iTunes Store turns 10 this month and it's worth looking back at the history of the online media shop to see how far it's come.

When the iTunes Store first debuted in 2003, the music industry was still grappling with the consequences of Napster's unprecedented success. By introducing an a la carte payment option in which users could purchase individual tracks for $0.99, Apple's iTunes Store quickly became the largest online destination for legal music downloads.

According to Forbes, iTunes is the top music retailer in the U.S., earning $2.4 billion in music, movie, app and book sales in just the last quarter.

To a large extent, Apple designed the iTunes Store out of sheer necessity. By April of 2003, there was already intense interest in the iPod, however there wasn't really a simple method of downloading music for the new device.

At first, the iTunes Store was comparably small — carrying only 200,000 tracks compared to the 26 million it currently has. What Apple had in spades, however, was the support of the record labels, which was crucial in creating the foothold in the music industry that Apple was able to acquire.   

Initially, the major record labels all signed one-year agreements with Apple. By the time the agreements had expired, iTunes was such a runaway success that Steve Jobs would have the upper hand in all future negotiations between Apple and the recording industry. In its first week, the iTunes Store sold one million tracks (keep in mind only 200,000 were available) and by the end of September, it had sold nearly 10 million.