The Visitors Report in Knowledgebase has always used Portal Sessions to calculate the number of visits to Portal Style 1, 2, or 3 portals. Sessions are used to perform multiple actions in the Customer Portal, but only some unique sessions are counted for the purposes of tallying the Visitors Report.
When an IP address accesses a page in a Moxie Knowledgebase Customer Portal (whether originating from a user's browser or via automated scripts such as a monitoring application, snap-ins, API, et cetera) it establishes an IIS session with its first action. This unique first action creates a session ID. Only these unique first sessions are recorded as visits for the Visitor report.
All subsequent actions taken under that same session ID are not counted as new visits. Provided the session remains alive and retains the same session ID, additional actions (such as returning to the portal main page) do not add to the portal's visit count. Only when that session is terminated and a new session ID is created will a new visit be counted for the portal.