The Pop 100 Airplay was a chart created in 2005 and released weekly by Billboard in the United States. It measured mainstream radio airplay, and was one of the three component charts, along with the Hot 100 Singles Sales and Hot Digital Songs charts, that determined the chart positions of singles on the Pop 100 chart. While the Pop 100 Airplay was discontinued from the official Billboard website and magazine in June 2009, the chart was published on billboard.biz until the week of August 22, 2009.[dead link]
The Pop 100 Airplay was often mistaken and confused with the Top 40 Mainstream chart. The Top 40 Mainstream chart and the Pop 100 Airplay both measured airplay of songs on mainstream radio stations playing pop-oriented music, but the Pop 100 Airplay (like the Hot 100 Airplay) measured airplay based on statistical audience impressions, while the Top 40 Mainstream uses the number of total detections. The Pop 100 Airplay replaced the Top 40 Tracks chart.