Billboard Hot 100
Since February 12, 2005, the Billboard Hot 100 tracks paid digital downloads from such internet services as iTunes, Napster, Musicmatch, and Rhapsody. With paid digital downloads added to the airplay/sales formula of the Hot 100, many songs benefited on the charts from the change. Billboard initially started tracking downloads in 2003 with the Hot Digital Tracks chart. However, these downloads did not count towards the Hot 100 and that chart (as opposed to Hot Digital Songs) counted each version of a song separately (the chart still exists today along with Hot Digital Songs).  This is the first major overhaul of the Hot 100's chart formula since December 1998.