Scrobbling means submitting listening information to Last.fm and/or Libre.fm; you can then get music recommendations and view your listening history and statistics. Most media players will work. Older android versions pre-Lollipop, the media player that you use must be able to work with the API e.g. https://f-droid.org/packages/org.kreed.vanilla or https://f-droid.org/packages/jp.co.kayo.android.localplayer. Apps can also hook into the Now-Playing broadcast: for example, https://f-droid.org/packages/com.jlyr can use it to grab lyrics. More info about scrobbling can be found on <a href="http://www.last.fm/help/faq?category=Scrobbling#201">Last.fm's FAQ</a>.