Design patterns·The shape of the whole application
someone added a feature by dropping in a package, and you did not change or redeploy the application to allow it.
Plugin architecture
Also calledplug-in, extension point, plugin system
Any design where third-party or optional code is discovered and loaded against a published extension point at runtime. It is the practical form of the open–closed principle at application scale, using late binding to make the extension possible without a rebuild. The costs are the ones every extensible product carries: a versioned contract, a trust boundary and failure isolation, because a plugin's crash is your crash.