Page groups are groups for the pages on your site.  Its an easy way for you to locate a certain type of page.  (you can organize your pages into any group structure you want)

And only you will see this structure in your members area.  The structure will not reflect how your site is viewed at all.

let's take a look at some examples of page groups and how to add them.

The red highlighted area are some examples of page groups.  By default you will have a page group for EACH  module that you have.  Because there are corresponding pages for those modules.

In this example I've added the page group "Active Site Pages".  The rest of the page groups are there by default and cannot be removed.  Because I like to make clones of my pages, I keep the clones de-activated in the "Default group".  And then I can easily find the pages I use on this site under the "Active Site Pages" Page group.  Since this site doesn't have a complicated structure that is all I needed for it.  But you can create page groups for all kinds of scenarios.  Like if you have restricted pages for certain users, you can have a page group for each users group.  This will not grant access to those groups, but will make the pages easier to locate when you are needing to make a change to those user pages.

Let's take a look at how to add a page group:

Go to YourSite.com > Page List, and then next to the "add group" button enter the name you wish to use for your new page group.  Then click the "add group " button.

Once the new group is added you can start creating pages for that group or move existing pages to the new group.  Here is how you can do that.

In the Page Settings of an existing page (or on the settings page when adding a new page) you can select the new group.