Extensions to &GStreamer; can be made using a plugin mechanism. This is used extensively in &GStreamer; even if only the standard package is being used: a few very basic functions reside in the core library, and all others are implemented in plugins. Plugins are only loaded when needed: a plugin registry is used to store the details of the plugins so that it is not neccessary to load all plugins to determine which are needed. This registry needs to be updated whenever a new plugin is added to the system: see the gst-register utility and the documentation in the &GstAppDevMan; for more details. User extensions to &GStreamer; can be installed in the main plugin directory, and will immediately be available for use in applications. gst-register should be run to update the repository: but the system should work correctly even if it hasn't been - it will just take longer to load the correct plugin. User specific plugin directories and registries will be available in future versions of &GStreamer;.