The user namespace provides a namespace for naming human users in a computing environment. User names are identified by the prefixes user/or _user/.
Users are named in user contexts. The user context has a single-level namespace and contains bindings of user names to user contexts. A user context allows you to name objects relative to a user, such as files, services, or resources associated with the user.
In the Solaris environment, user names correspond to Solaris login IDs. For example, _user/inga identifies a user whose login ID is inga.