According to Billboard:

“The YouTube streaming datais now factored into the chart’s ranking, enhancing a formula that includes Nielsen’s digital download track sales and physical singles sales; as well as terrestrial radio airplay, on-demand audio streaming, and online radio streaming, also tracked by Nielsen.

Billboard is now incorporating all official videos on YouTube captured by Nielsen’s streaming measurement, including Vevo on YouTube, and user-generated clips that utilize authorized audio into the Hot 100 and the Hot 100 formula-based genre charts – Hot Country Songs, Hot R&B/Hip-Hop Songs, R&B Songs Rap Songs, Hot Latin Songs, Hot Rock Songs and Dance/Electronic Songs – to further reflect the divergent platforms for music consumption in today’s world.”