https://www.theverge.com/2017/9/26/16365354/alexa-amazon-music-app

Voice assistant Alexa is now available in the Amazon Music app on both iOS and Android. Users in the US, UK, Germany, and Austria can access the feature by hitting the Alexa button available throughout the app. Users can ask for Alexa to play music by genre, decade, mood, tempo, activity, and even lyrics (if you’ve forgotten the song name for instance).

The feature is designed for when users don’t have two hands, or the attention required, to dedicate to their phone; or for those already adapted to asking Alexa to play music in their homes. Alexa will respond to instructions like: “play the song of the day,” “play music for cleaning,” or “play the new Foo Fighters album.”