Network effect
Etymology
A plain modern compound: "network" (originally a net-like mesh of threads) plus "effect." Economists adopted it to name the way each additional user of a telephone, a language, or a marketplace raises its value for everyone already in it.
noun · /NET-wurk ih-FEKT/
When a product or service becomes more valuable the more people use it.
What it names
Why some platforms become nearly impossible to leave or unseat — value compounds with every new user.
Example
The messaging app won not because it was better but because of the network effect — everyone you knew was already on it.
Related idea
Lock-in is often the result; path dependence explains why an inferior standard can win and then stay.