It was a hashtag contest!! fans were asked to participate and the contest was open till 14th December,2018. Those of tu who are a member of the official website are well aware that the response was good and everyone did enjoy participating in the "hashtag" contest. They asked our imagination to run wild and from the whole loads of comments, few hashtag that i liked were - #believeinwinx, #winxforever15, #15yearsoftogethernes......
Eventually the winner was also anncounced in the official instagram handle of winxclub... The winning hashtag was - #15yearsofwinx
