All users are authenticated when they attempt to gain access to the Web sites, folders, and files on your Web server. Users do not have to enter a user name and password.
All Web browsers support anonymous access.
Basic Basic authentication requires all users to have a Windows NT account to log on to a server. Users must enter a user name and password. Most Web browsers support Basic authentication. Users do not have to enter a user name and password when they log on to a server. Anonymous Anonymous access lets users who do not have Windows NT accounts connect to the server and use server resources.