Google Music used to allow you to rate your songs from one to five stars. Though it was a feature that you had to add on, for those of us who did add it, we used it all the time to help sort and organize our music. Today - May 14, 2015 - Google removed this option. This is their response:

"We've decided to remove the 5-star Rating lab. This decision wasn't made lightly, but Thumbs Up/Down is integral for the future vision for Play Music and will be a central design point for our future releases."

Music isn't binary. Though the 5 Star rating system isn't terribly nuanced, many people relied on it.

If you want to bring it back, please sign the petition.