Since first opening in 2003, iTunes has changed the landscape of the music industry. It has helped to mold the way in which music is purchased, and has challenged artists to market themselves using a digital model. The online store has come a long way, now approaching 10 billion songs downloaded.

To celebrate the benchmark, Apple will hold a “Countdown to 10 billion Songs” contest, giving $10,000 worth of an iTunes gift certificate to the lucky person who purchases the 10 billionth song from its store.

In addition, the company revealed its best-selling tracks on iTunes since it first began. Black Eyed Peas’ “I Gotta Feeling,” made the top spot on the list, while Flo Rida’s “Low” featuring T-Pain came it at number 7.

Also making the list were Lady Gaga’s “Poker Face” and “Just Dance,” as well as newcomer Ke$ha‘s “Tik Tok.”