Comment by globular-toast

> An API (Application Programming Interface) is a set of rules that allow two systems to communicate. In the web world, REST APIs ... are by far the most widespread.

I too had this overly restrictive view of "APIs" for too long. One I started to think about it as the interface between any teo software components it really changed the way I did programming. In other words, a system itself is composed and that composition is done via APIs. There's no point treating "the API" as something special.