Published by Billboard magazine, the data are compiled by Nielsen SoundScan based collectively on each single's weekly physical and digital sales, airplay, and, since 2012, streaming.
A new chart is compiled and officially released to the public every Tuesday in Billboard magazine and on its website.
Mariah Carey's "All I Want for Christmas Is You" began the 2020s in the number-one position on the Hot 100, and made her the first artist to rank at number one on charts from four different decades.
The following week, on January 11, 2020, Post Malone's "Circles" returned to the number-one spot, another carry-over from the 2010s; it originally reached number one on November 30, 2019.
[2] Note: The best-performing single on the Billboard Hot 100 of 2021 was Dua Lipa's "Levitating", which peaked at number two, and thus is excluded here.