Tracks and Songs
In recognition of the increasing sales of digitally downloaded music, Billboard created the Hot Digital Tracks chart in 2003. This chart ranks the sales of legally purchased online digital tracks from a wide variety of retailers. In 2005 this data was incorporated into charts like the Hot 100 and Pop 100 out of recognition that digital sales were more reliable in measuring the popularity of a current single than traditional store sales of a single. Currently, many popular singles are unavailable for purchase in a traditional store, but almost all popular singles are available for purchase as a digitally downloaded track.
Billboard also now publishes a Hot Digital Songs chart as well. This chart combines multiple versions (including remixes) of a song by an artist to measure the popularity of a song. It is part of Billboard's gradual migration to focusing on charting popularity of songs instead of a specific single configuration. The first Billboard singles charts focused on the popularity of a particular recording released on a 45. Today, a song's popularity is determined by a combination of sales and radio airplay in many possible configurations.
