Site Groups in SharePoint Designer 2010 relate to SharePoint groups and site permissions. Selecting the Site Groups tab, shown in Figure 7.51, provides access to all the existing SharePoint groups within the current site, along with options for creating new SharePoint groups, adding and removing users, and assigning existing permission levels to groups. Again, this functionality is new to SharePoint Designer 2010. Previously, in SharePoint Designer 2007, it was necessary to modify settings such as SharePoint groups and group membership via the Web interface. You can also access SharePoint permission settings via the Home tab settings page.
You can access the following tasks via the Site Groups tab.