Design

A technique that I have been using for a very long time to enable the inner workings of code to be cleaner and more decoupled, easier to maintain and extend.

In essence it is nothing that new - event driven systems have been around for a very long time.
What makes this way of doing things different is that it is very lightweight.

There simply isn't an application or software system that wouldn't be improved by having a plugin architecture - but it seems harder to implement.