  The magnetic community continues to discuss the possibility to observe the
magnetic superfluidity, despite the fact that it has been discovered long time
ago. It was observed in antiferromagnetic states of superfluid $^3$He in 1984.
In this article we reminds the main principles of spin superfluidity and
related Bose-Einstain magnon condensation. We discuss applications of this
phenomenon in supermagnonic devises.
