Sub-user functionality allows you to register additional accounts under your account. This way, you do not have to share your login credentials to Clicky with anyone, and you can assign each user access to view the reports for only the sites they need access to. Each user can be assigned "read-only" or "admin" access to each site. Admin access is needed to change any preferences, setup goals, etc. The only thing an admin can't do is delete the site.