Billboard's Hot 100 Countdown is a weekly chart that ranks the top 100 songs in the United States based on sales, radio airplay, and online streaming. It is published by Billboard magazine and serves as a key indicator of a song's popularity and commercial success. The chart has been in existence since 1958 and includes a diverse range of music genres. Artists and songs that reach the top of the Hot 100 often gain significant recognition and can influence trends in the music industry.