Roles and permissions are the properties of the user. Roles are predefined sets of privileges that permit access to different levels of physical and virtual resources. Multilevel administration provides a finely grained hierarchy of permissions. For example, a data center administrator has permissions to manage all objects in the data center, while a host administrator has system administrator permissions to a single physical host. A user can have permissions to use a single virtual machine but not make any changes to the virtual machine configurations, while another user can be assigned system permissions to a virtual machine.