Shack User Switching allows you to test any user account on your sites, without compromising their passwords. With one click, you can browse your site and see exactly what your users see. This is a safe and useful way to troubleshoot problems for your site's users.
Normally, to test a user account, you will need to access or change their password. With Shack User Switching, the users' passwords remain private and secure. This video is a great introduction to how Shack User Switching works: