A permission is set on an object in the vCenter object hierarchy. Each permission associates the object with a group or user and the group's or user's access roles. For example, you can select a virtual machine object, add one permission that gives the ReadOnly role to Group 1, and add a second permission that gives the Administrator role to User 2.
By assigning a different role to a group of users on different objects, you control the tasks that those users can perform in your vSphere environment. For example, to allow a group to configure memory for the host, select that host and add a permission that grants a role to that group that includes theprivilege.
For conceptual information about permissions, see the discussion in Understanding the Object-Level Permission Model.
You can assign permissions to objects at different levels of the hierarchy, for example, you can assign permissions to a host object or to a folder object that includes all host objects. See Hierarchical Inheritance of Permissions. You can also assign permissions to a global root object to apply the permissions to all object in all solutions. See Global Permissions.