While music discovery services revolve around people exposing their listening habits (a lot of people who listen to A, B and C also listen to D, so if you like A, B and C then you'll probably also like D; or if you know you have similar tastes to a particular person, then it's worth sampling tracks they've started listening to).
But you might not want to share your habits with all and sundry.
Consequently, Rdio has added the ability to protect accounts, which means users get to approve would-be followers before they get to see your collection, playlists, activity, and full profile.
The default is still public, which is a bit naughty.
It's up to users to visit the Advanced tab in their settings and switch to Protected instead of Public.
A monthly subscription costs $8.90 for browser or desktop use, or $12.90 per month for web streaming plus streaming to a smartphone or Sonos or Roku players.
A free 7-day trial is available.