Scale-free network
A scale-free network is a network whose degree distribution follows a power law, at least asymptotically. That is, the fraction P(k) of nodes in the network having k connections to other nodes goes for large values of k as
$ P(k) ～ k^{-\gamma}
where $ \gamma is a parameter whose value is typically in the range $ 2<\gamma<3(wherein the second moment (scale parameter) of $ k^{-\gamma}is infinite but the first moment is finite), although occasionally it may lie outside these bounds.
https://www.youtube.com/watch?v=pYMsI-8GsxI