The class store is part of the Zero Administration Windows Application Management Features. (For more information on Zero Administration Windows, see Meeting Enterprise Needs.) Assigned applications are installed whenever a user logs on. This installation is broken down into multiple stages. The first stage includes system-related activation information, such as COM, Shell, and Icons. Subsequent installation stages are performed by the Microsoft installer technology setup engine, and can include incremental installation of components as required by the application.
Published applications are available to the user but are only installed when needed. The class store is used to locate installation packages by using identifiers such as the CLSID or file extension. The installation is identical to that of the installation of assigned packages. Published applications can also be installed using Add/Remove programs.