Billboard, iTunes and Official Charts track the top 100 most successful singles. Billboard's Hot 100 focuses on U.S. singles. iTunes U.S. storefront features the top 100 songs in the United States. Official Charts tracks the top 100 singles for the U.K. Ranks are determined by each company’s proprietary formula.
Billboard’s Hot 100 ranks songs each week based on digital and physical sales and audience streaming of the single’s audio and video (as monitored by Nielsen Music). iTunes ranks its top 100 songs on a continuous basis; however, iTunes does not explain how it weighs or ranks each track’s success; it’s unknown whether or not it’s based purely on sales. Official Charts tracks weekly sales of the top U.K. singles based on digital and physical sales and the frequency of each track’s audio streaming.
Billboard’s Hot 100 debuted in 1958. As of its 50th anniversary in 2013, the top performing artists of all time on Billboard's Hot 100 include The Beatles, Madonna, Elton John, Elvis Presley and Stevie Wonder. The top-performing Hot 100 singles of all time include Elvis Presley’s “Are You Lonesome Tonight?,” "Aquarius/Let the Sunshine In" by The 5th Dimension, "Tik Tok" by Ke$ha, and "Hey Jude" by The Beatles.