A principle that states the value of a network increases with the numbers of its users. The value is believed to increase as a square root of the number of users, thus, showing a practical way to evaluate the worth of Bitcoin, Ethereum and any social media company.
Diagrams

Originated from/Coined by
Robert Metcalfe
Further Reading/ References
https://medium.com/@clearblocks/valuing-bitcoin-and-ethereum-with-metcalfes-law-aaa743f469f6
https://en.wikipedia.org/wiki/Metcalfe%27s_law
https://amplitude.com/blog/2017/06/13/network-effect-product-growth
