On the organization page, you can filter so that only a specific small group or a several small groups are displayed. Just click the button below the toolbar - filter by name/group to open the dialog box. There are 2 filters: Name Filter and Small Group Filter.
This is helpful in very large organization as it allows you to find a person by name.
NOTE: If you use the Filter by name feature, do not use the toolbar to email or run reports for that individual. Just click on their name and go directly to their people page.
This is useful for communicating with one or more small groups at a time as you can filter for just one group, select several groups, or select a range of groups.
After you have selected your groups and clicked OK, you will be back at the organization page with only those who are in the selected group/groups displaying. At that point you can use the toolbar to send emails, run reports, etc.