Prior to 1955, Billboard did not have a unified, all-encompassing popularity chart, instead measuring songs by individual metrics. At the start of the rock era in 1955, three such charts existed:
- Best Sellers in Stores was the first Billboard chart, established in 1936. This chart ranked the biggest selling singles in retail stores, as reported by merchants surveyed throughout the country (20 to 50 positions).
- Most Played by Jockeys was Billboard's original airplay chart. It ranked the most played songs on United States radio stations, as reported by radio disc jockeys and radio stations (20 to 25 positions).
- Most Played in Jukeboxes ranked the most played songs in jukeboxes across the United States (20 positions). This was one of the main outlets of measuring song popularity with the younger generation of music listeners, as many radio stations resisted adding rock and roll music to their playlists for many years.
Although officially all three charts had equal "weight" in terms of their importance, Billboard Magazine considers the Best Sellers in Stores chart when referencing a song's performance prior to the creation of the Hot 100. On the week ending November 12, 1955, Billboard published The Top 100 for the first time. The Top 100 combined all aspects of a single's performance (sales, airplay and jukebox activity), based on a point system that typically gave sales (purchases) more weight than radio airplay. The Best Sellers In Stores, Most Played by Jockeys and Most Played in Jukeboxes charts continued to be published concurrently with the new Top 100 chart.
On June 17, 1957, Billboard discontinued the Most Played in Jukeboxes chart, as the popularity of jukeboxes waned and radio stations incorporated more and more rock-oriented music into their playlists. The week ending July 28, 1958 was the final publication of the Most Played By Jockeys and Top 100 charts, both of which had Perez Prado's instrumental version of "Patricia" ascending to the top.
On August 4, 1958, Billboard premiered one main all-genre singles chart: the Hot 100. The Hot 100 quickly became the industry standard and Billboard discontinued the Best Sellers In Stores chart on October 13, 1958.
The Billboard Hot 100 is still the standard by which a song's popularity is measured in the United States. The Hot 100 is ranked by radio airplay audience impressions as measured by Nielsen BDS, sales data compiled by Nielsen Soundscan (both at retail and digitally) and streaming activity provided by online music sources.
There are several component charts that contribute to the overall calculation of the Hot 100. The most significant ones are:
- Hot 100 Airplay: (per Billboard) approximately 1,000 stations, "composed of adult contemporary, R&B, hip hop, country, rock, gospel, Latin and Christian formats, digitally monitored twenty-four hours a day, seven days a week. Charts are ranked by number of gross audience impressions, computed by cross-referencing exact times of radio airplay with Arbitron listener data."
- Hot Singles Sales: (per Billboard) "the top selling singles compiled from a national sample of retail store, mass merchant and internet sales reports collected, compiled, and provided by Nielsen SoundScan." The chart is released weekly and measures sales of physical commercial singles. With the decline in sales of physical singles in the US, many songs that become number one on this chart often do not even chart on the Hot 100.
- Hot Digital Songs: Digital sales are tracked by Nielsen SoundScan and are included as part of a title's sales points.
- Streaming Songs: a collaboration between Billboard, Nielsen SoundScan and National Association of Recording Merchandisers which measures the top streamed radio songs, on-demand songs and videos on leading online music services.