This section shows the number of first-time and returning visitors to your site. Only visitors who identified by cookies are counted.
First-time visitors are defined as those who didn't have a cookie on their first hit, but had one subsequently.
Returning visitors already had a cookie when they visited your site during the period covered in this report.
If the data shows that all users did not have cookies, it is likely that the Reporting Server has not been configured to perform this analysis. Contact your system administrator to see if this feature has been enabled.

 By tracking the ratio between new and returning visitors over a period of time, you can determine if your site is attracting enough repeat visitors.