Gap in Service - A period of time during which there are no requests, in a single log file, which is longer than seems justified given the average level of traffic on the server. These frequently represent periods when the server was down or had lost its Internet connection, but could also represent failures in the logging system, corrupt log files, or times which just happen to not have any requests. Goal - Summary can be configured to track which visits contain requests that you specify as being the Goal. The number of visits which contain requests matching the pattern is tracked for each referring domain, search phrase, and search word. Graphic - A request for a file containing an image.
Summary uses the file name extension to determine if a request is for a graphic.
The set of extensions used to make this determination can be configured . Requests for graphics are not counted as steps in a visit. Hijacks - The number of visits accessing only graphics. This can happen for any of several reasons. One common cause is other web sites including your graphics on their pages.