User Access Control (UAC) is a feature that allows you to restrict entry to your website. Individuals without the correct username and password won't be able to enter your site. This could be used for things such as internal company websites or a trade site.

By enabling UAC, you'll be able to create and manage a list of users who you would like to grant access to your site.

Tip: Inside the website editor there are other ways to restrict access to your website. For simple requirements you can set a basic password for a set of pages You could also use "IP address restriction", which restricts access to specific IP addresses.