The Law
In economics, a network effect is a positive benefit created by a new user buying a product or joining a service. In the context of computer networks, these benefits are commonly believed to scale quickly with the number of users.
In technology circles, perhaps the best known instantiation of network effects is Metcalfe’s Law, named for Ethernet co-inventor Bob Metcalfe, who was likely inspired by similar theories developed at Bell Telephone in the early 20th century.
This law concerned the value of the Ethernet network cards sold by Metcalfe’s company 3Com. It states that given a network with N users, buying one additional Ethernet card provides you with N new possible network connections (e.g., from the new card to each of the N existing users).
It then follows, roughly speaking, that the value of N network cards grows as N^2 instead of N. Once a network achieves a certain critical size, therefore, the value it returns will quickly begin to far exceed the cost of joining it, creating a powerful positive feedback loop.
Metcalfe’s Law is incredibly influential in Silicon Valley, where it’s often applied to justify the monopoly status of the social media conglomerates. If a network like Facebook has over a 1,000,000,000 users, the law tells us, then its value to users grows as (1,000,000,000)^2 — a quantity so vast that any attempt to compete with this giant must be futile.
It’s widely believed among many Silicon Valley types that this calculus helps explains the lack of venture capital investment in new social media start-ups in recent years. The power of network effects in this sector is unimpeachable.
But should they be?






