Apple Music stars on the song means?

[Closingracer]

What do the stars mean on the songs in the app? I have a feeling I might know but Idk for sure and wondering what it means.

 

[Nozuka]

They mark the most popular songs.

 

[Futhark]

I thought it was the singles off the album but could be wrong

 

[Closingracer]

They mark the most popular songs.

Only for albums? Cause Closer which is the best selling song on iTunes currently doesn't have one I think

Edit: nm it does but not in playlists

 

[thiagueirass]

The star marks the most popular songs in a album.