Metcalfe's Law

In network theory, the value of a system grows as approximately the square of the number of users of the system.

This law is based on the number of possible pairwise connections within a system and is closely related to Reed's Law. Odlyzko and others have argued that both Reed's Law and Metcalfe's Law overstate the value of the system by not accounting for the limits of human cognition on network effects; see Dunbar's Number.