The HTTP protocol provides a basic functionality for authenticating users. When a request is sent to a protected site, or a protected area within a site, the browser presents the user with a prompt for name and password. If the provided values match an authorized user, access to the site is granted.
Note
The basic HTTP authentication method is simple to set up on Apache, especially with assistance from Webmin. The main drawback to this functionality is that it isn't very secure or customizable. If you plan to use this form of authentication on the open Internet, make sure you use it in combination with the encrypted HTTPS protocol.
Before starting, make sure that the module auth_basic is enabled in your Apache configuration. Take a look at the recipe Enabling Apache modules for more information.