A very powerful function in DotNetNuke is user-registration and the roles which can be assigned to them. It is possible to create different kind of roles and so users can have access on different security levels. If a user with a specific role logs on to the portal, it only has access to the information which it ought to see. It is so flexible, that you can assign another skin to a page which is only visible to this role (there can be multiple roles assigned to a page). Another aspect is that you can assign roles to individual modules. So you can have one page with a lot of modules each visible for only a group of people.