Webtrends Analytics 9 Adminstration Guide, November 2012
You can filter Webtrends Analytics 9 data by including or excluding either individual hits or entire visitor sessions.
Hit filters include or exclude raw data generated by individual actions on a website. A hit is an individual request for a page, file, or image. For example, when a user requests a web page, the user can incidentally generate hits to the .htm page itself, to several .gif image files, and to the .css file that stores the formatting for the page. A Hit filter includes or excludes each of these hits individually. For example, if you create a Hit filter to exclude all .gif, .jpg, and .bmp files, Webtrends analyzes data about page requests, but ignores data about requests for the images embedded in pages.
Visit filters include or exclude data that has already been grouped into visits. A visit is a single session of activity identified with an individual user, including all the page requests and hits logged during that session.
When you use a profile-level visit filter, Webtrends checks the first hit of a visit against the filter and then includes or excludes all the data contained in the visit based on whether it matches the criteria. For example, if you create a profile-level filter to include all visits that use the entry page www.zedesco.com\sale.htm, Webtrends checks the first hit in the visit to determine the entry page, analyzes only data for visits that originated on the specified entry page, and ignores all data associated with visits that originated on other pages. This works because profile-level visit filters track criteria that occur on the first hit of the visit.
When filtering custom report visit filters, however, Webtrends checks all hits in a visit to match visit criteria. For example, to filter URL Viewed in Visit, Webtrends needs to check every hit to determine if the specified URL was accessed during the visit.
When you combine hit and visit filters in the same profile or custom report, Webtrends processes the hit filters first and then the visit filters.