This term was used originally to show the load on the hardware systems. In the immature Internet market, this number was touted as a sign of activity. This was meaningless to an advertiser since it didn't reflect the number of times a particular ad was seen by a visitor. Several systems have been designed to more accurately represent and track this data. These sophisticated and costly server-based trackings are not available to me.
Every page has one or more counters on it.
Some have multiple counters. Every page on the site maintains a unique counter provided by America Online. These counters are located at the bottom of every page, taking last priority in the loading. This requires the user to be on a page long enough for most of the page to load before AOL will register a visit to the page. The Advertisement is always the first image on the page and has the best opportunity to be completely delivered.