A new music streaming service has been launched with the help of some of the biggest names in entertainment.

Rapper Jay Z has launched Tidal, which is co-owned by Madonna, Rihanna, Beyonce, Kanye West and Alicia Keys.

It's been billed as the first artist-owned platform for music and video.

It hopes to address musicians' concerns that they are losing out financially in an age of music downloads and booming streaming services.

Many musicians turned their profile pictures to turquoise and encouraged their followers to do the same, as well as sharing a Tidal hashtag.

But there's been a fan backlash over activism tactics being used to promote musicians earning more money, rather than using their voices to publicise a genuine charity campaign.