scale-free networks

This is a network which has large hubs (aka a few nodes which are densely connected). The amount by which degrees are distributed along a power law distribution.

For undirected networks, the formula $P_{\text{deg}}(k)\propto k^{-\gamma }$ is the degree distribution. $P_{\text{deg}}(k)$ decays as k increases (which represents the likelihood of finding a node with a large degree).

The naming of something as scale-free networks are controversial, because they may also be a log-normal distribution.