# Network Effects

Networks rule our world. From the chemical reaction pathways inside a cell, to the web of relationships in an ecosystem, to the trade and political networks that shape the course of history.

[Network effects occur when the value of a product or service is subject to the number of users. A positive network effect means that a product or service becomes more valuable to its users as more people use it.](https://julian.digital/2021/12/20/the-power-of-defaults/)

Network [diffusion](http://web.archive.org/web/20240705113531/https://meltingasphalt.com/interactive/going-critical/) is the way things move and spread, somewhat chaotically, across a network. For example:

- Infectious diseases jumping from host to host within a population.
- Memes spreading across a follower graph on social media.
- A wildfire breaking out across a landscape.
- Ideas and practices diffusing through a [[culture]].
- Neutrons cascading through a hunk of enriched uranium.
- Economies of scale. More scale means more scale.
- More customers means more social proof means more customers.