If you want to create a website that only a selected group of individuals should be able to access, with Drupal this is a piece of cake. If recently a private website and was very impressed how easy this is.
Some refer to this an intranet stite, which is wrong. If you have and intranet, that is web services within a local area network, chances are you don't need to bother with access control in any way, since access is handled on a network level. You might still have restricted sites, that only a selected group of individuals should be able to access, this is a private intranet site.
What I am coming to is:
How do you restrict access, that is lockdown Drupal?