Pandora is a music-streaming service with access to a vast library of albums, artists, playlists, and podcasts.
The app emphasizes curation and recommendations, allowing users to build algorithmically linked "stations" based on music preferences.
Stations become more attuned to preferences the more you listen.
Pandora offers one free tier (with ads) and two paid tiers: Pandora Plus and Pandora Premium.
Why Pandora is important for the Billboard charts
Pandora offers two paid tiers: Plus and Premium. Only Pandora Premium qualifies as paid on-demand streaming and counts favorably towards Billboard charts.
Pandora Plus doesn't count as ad-supported, because the tier doesn't have ads; however, it's considered non-interactive radio rather than on-demand streaming for Billboard charts.
Pandora Premium counts towards Billboard, because Billboard only credits streams where the listener has full control, and Pandora Premium is the only tier that meets that standard. Pandora Plus is paid, ad-free but still radio based and song selection is limited and algorithm controlled.