A configuration is the set of plug-ins available in a particular instance of the Eclipse Platform. A given installation of Eclipse may contain hundreds or even thousands of plug-ins. More than one Eclipse-based application can share this same install location, but they don't always want to use all the same plug-ins. When Eclipse is started, a configurator determines what subset of the installed pool of plug-ins will be used for that particular instance of the platform. By default, all installed plug-ins will be in the configuration, but a configuration can be customized to contain different groups of plug-ins. Go to Help > Software Updates > Manage Configuration to see and modify what plug-ins are in your configuration.