The iTunes Store said Tuesday it had passed a milestone, selling more than 3 billion songs since launching four years ago. The milestone came just six months after iTunes, Apple Inc.'s online music download service, surpassed the 2 billion tracks-sold mark. The service launched in April 2003 and it took until February 2006 to sell its first 1 billion songs.
In the first quarter of this year, it was ranked the third-biggest overall music retailer in the U.S., behind No. 1 Wal-Mart Stores Inc. and Best Buy Co., according to consumer surveys by The NPD Group. The ranking was based on units sold, not revenue from sales, and counted every 12 tracks purchased online as equivalent to an album in compact disc format. Apple's line of iPod portable music players has been key to iTunes' popularity.