'Group Access' is the name given to the process of restricting certain pages on the site to certain categories of user, normally by using a password.  In other words, users have to log on before they can look at certain pages.

Depending on the complexities and requirements of your site, group access can get much more complicated that this, but that's the basic principle!

There is an excellent component that can achieve this and more .  For example:

• You can create any number of User Groups for both the front-end (users) and back-end (administrators) of your website and then assign each page access rights.
• You can assign users to multiple Groups, enabling them to have specific access rights catered exactly to them.  Your website will not just be dynamic, but personal too.
• You can create and distribute Access Codes which automatically add a user to a particular Group when the access code is submitted, which then opens up further site content if a user is a member of a particular group.  To prevent Access Code misuse, you can limit the number of times a code may be used, as well as indicate valid times for its use.