A music download is the transferral of a song from an Internet-facing computer or website to a user's computer. This term is used can mean both legal downloads and downloads of copyright material without permission or paying.
As of 2006, digital music sales are estimated to have reached approximately US$2 billion. Around the world in 2006, an estimated 509 million songs were purchased online. Sites such as iTunes Store and Zune Marketplace sell music to be downloaded. As of January 2011[update], Apple's iTunes Store alone had an income of $1.1 billion.