OSGi (Open Services Gateway initiative) is a Java-based module system and service platform that provides a dynamic component model for building extensible applications. dotCMS plugins are built using OSGi, which can include a combination of Java classes, JARs, static assets, HTML, and Velocity templates. dotCMS plugins are hot-loadable, meaning they can be installed at runtime and do not require a server restart to take effect. This makes OSGi not just a partner in the traditional sense, but a core architectural feature of dotCMS that enables its extensibility. OSGi plugins provide methods to easily implement new functionality via understandable extension points, including REST endpoints, Viewtools, Actionlets, services, interceptors, custom admin tools, and content hooks.