The Billboard Hot 100 is the United States music industry standard singles popularity chart issued weekly by Billboard magazine. Chart rankings are based on airplay and sales; the tracking-week for sales begins on Monday and ends on Sunday; while the airplay tracking-week runs from Wednesday to Tuesday. A new chart is compiled and officially released to the public by Billboard on Thursday. Each chart is dated with the "week-ending" date of the following Saturday. ::Monday, January 1 – sales tracking-week begins ::Sunday, January 7 – sales tracking-week ends ::Thursday, January 11 – new chart released, with issue date of Saturday, January 20.

The first number one song of the Hot 100 era was "Poor Little Fool" by Ricky Nelson on August 4, 1958. As of the issue dated March 22 2008, the Hot 100 has had 955 number-one hits. Its current number one is "Love in This Club" by Usher featuring Young Jeezy.