Billboard is an American magazine now devoted to the music industry. When founded in 1894 it was originally concerned with carnival entertainment, but music coverage grew to the point that its earlier subjects were spun off into a separate journal in the 1950s.
Today, it maintains several internationally for pop charts that track the most popular songs in various categories on a weekly basis. Its "Hot 100" survey ranks the top 100 pop songs and is frequently used as the standard measure for ranking singles in the United States. The Hot 100 chart is compiled by tracking single sales as well as songs' radio airplay on a variety of different station formats, including Urban, Modern Rock, Country, Adult Contemporary, Top 40, Rhythmic, and Adult Top 40. Currently, because few musicians release singles in America anymore, Billboard weights a song's radio play as 80 percent and its single sales as 20 percent to calculate the weekly Hot 100 rankings.
Since late 1998, it has been possible for a song to chart on the Hot 100 based only on airplay points (the term that Billboard uses for this is an album cut). Prior to this change, a song had to have had a single available for purchase in order to rank on the Hot 100. To date, several songs that have had no buyable single have managed to achieve such massive radio airplay that they were able to make it into the number one spot anyway. The first instance of this was Aaliyah's "Try Again" from Romeo Must Die, which was a giant pop, rhythmic, and urban radio hit.
Some other notable Billboard records include Mariah Carey and Boyz II Men's 1995 song "One Sweet Day," which is the longest-lasting number one on the Hot 100 (16 weeks) and consequently the most popular song, in general, in American history.
The classic Rock group Pink Floyd hold the record for the album in the top 100 the longest. Their 1973 Dark Side of the Moon remained on the chart for 591 consecutive weeks (11 years), and 740 weeks total.
Madonna, Elvis Presley, and The Beatles hold a majority of the other important Billboard records. For example, the three acts are the three with the most top five, top ten, and top twenty Hot 100 songs in Billboard history.
For many years, the weekly syndicated radio program "American Top 40", hosted by Casey Kasem, played the top 40 songs on that Billboard chart in reverse order. The October 11, 2003 chart week marked the first time since its inception that the Billboard Top 10 artists were exclusively black individuals or groups with a majority of black members.