Music charts such as the Billboard Hot 100 work on a points system, so the top 10 positions on those charts are determined by the system. A number of factors are involved in the system, including sales, airplay and streaming.
The Billboard charts are among the most influential charts in American music. For most of its history, it based its chart positions on a combination of sales and radio airplay. However, it added streaming music and digital music sales to its metrics in 2012 due to the growing number of streaming listeners and digital downloads. Billboard's current points position is based on 35 to 45 percent sales, 30 to 40 percent airplay and 20 to 30 percent streaming.
Songs usually need to have presence in all three mediums to top the Billboard charts; however, some songs may skew towards a specific medium. Traditionally, songs usually needed to be released as singles to climb the Billboard charts; however, the new metrics allow other songs to perform well based on downloads. For example, several songs from the Mumford & Sons album "Babel" hit top positions the Billboard rock charts due to online sales and streaming, even though those tracks were not released as singles.
Billboard uses similar metrics across its music charts, such as the Hot 100, Hot Country Songs and Hot R&B-Hip Hop Songs.