FAQ What is the Update Manager?
The Update Manager allows you to find new plug-ins on your machine, your network, or the Internet, compare new plug-ins to your configuration, and install only those that are compatible with your current configuration. The Update Manager thinks in terms of features, a logical group of related plug-ins, and also provides support for managing configurations to undo a given installation or to automatically update all the features currently installed in your Eclipse configuration.
Before plug-ins can be installed by the Update Manager, they need to be collected into a feature. The feature itself has to be published using an update site.
The Update Manager is invoked by Help > Software Updates.
Eclipse online article How to Keep Up to Date (http://www.eclipse.org/articles)