Qrator is an application that allows users to have a more nuanced control over how they rate their music. Instead of just rating songs from a scale of 1 to 5 or simply thumbing up or down songs, Qrator allows users to create custom fields by which to rate their music. This means that users can add fields such as "Lyrical Quality" or "Danceability" or anything they desire, and then rate their music in a way that is meaningful to them.
From a developer's perspective, having access to user sourced data that applies specific tags to songs allows one to have greater insights into how people perceive certain songs and genres, and using those insights one could make more effective use of targeted advertising.