Online advertisement represents a significant portion of Internet-related revenues.
However, no reliable and widespread system for metering Web site popularity has emerged. As a consequence, the market is dominated by the few very well-known sites, such as the main newspapers and the most effective search engines, because their popularity is taken as a given fact. For many sites of medium to high popularity there is a great potential for an increase of advertisement profits, but third party guaranties for their declared access rates is needed. There has been surprisingly little work on Web metering, and most of this work is not concerned with certified statistics. In fact, Web counting is a difficult and complex problem, raising many issues of different kinds.