The Billboard charts tabulate the relative weekly popularity of songs or albums in the United States. The results are published in Billboard magazine. The two primary charts – the Hot 100 (top 100 singles) and the Billboard 200 (top 200 albums) – factor in airplay, as well as music sales in all relevant formats.
On January 4, 1936, Billboard magazine published its first music hit parade. The first Music Popularity Chart was calculated in July 1940. A variety of song charts followed, which were eventually consolidated into the Hot 100 by mid-1958. The Hot 100 currently combines single sales, radio airplay and digital downloads.
All of Billboard's charts use this basic formula. What separates the charts is which stations and stores are used – each musical genre having a core audience or retail group. Each genre's department at Billboard is headed up by a chart manager, who makes these determinations.