Definitions:
Number of Sessions per Month: The average number of computer sessions per person for the specified reporting period. A session consists of Web sessions and/or any period of time spent using computer applications.

Number of Unique Domains Visited: An average of the total number of unique domains visited per person for the specified reporting period.

Page Views per Month: The total number of times a Web page has been requested by a user. Page views are counted only when they fully load into the users browser window. Pages accessed from the users local cache are included in page view counts. Unique pages will be counted each time they are requested.

Page Views per Surfing Session: Average number of Web pages viewed per person per Web session for the specified reporting period.

Time Spent per Month: Average time spent during active computer sessions per person for the specified reporting period.

Time Spent During Surfing Session: Average time spent per person during an active computer session for the specified reporting period.

Duration of a Page Viewed: Average duration of time that a Web page was viewed per person over the specified reporting period.

Internet Universe: The Nielsen//NetRatings Internet universe is defined as all members, 2 years of age or older, of households that currently have access to the Internet from a personal computer.

Active Internet Universe: People that have used a computer capable of connecting to the Internet AND visited a Web site and/or launched any computer file tracked by Nielsen//NetRatings applications metering module.