Page tagging

Concerns about the accuracy of logfile analysis in the presence of caching, and the desire to be able to perform web analytics as an outsourced service, led to the second data collection method, page tagging.

In the mid 1990s, Web counters were commonly seen — these were images included in a web page that showed the number of times the image had been requested, which was an estimate of the number of visits to that page. In the late 1990s this concept evolved to include a small invisible image instead of a visible one, and, by using JavaScript, to pass along with the image request certain information about the page and the visitor. This information can then be processed by a web analytics company, and extensive statistics generated. This can be done remotely, by the web analytics company.

The web analytics service also manages the process of assigning a cookie to the user, which can uniquely identify them during their visit and in subsequent visits.

Advantages of page tagging

The main advantages of page tagging over logfile analysis are as follows.

• The JavaScript is automatically run every time the page is loaded. Thus there are fewer worries about caching.
• It is easier to add additional information to the JavaScript, which can then be collected by the remote server. For example, information about the visitors' screen sizes, or the price of the goods they purchased, can be added in this way. With logfile analysis, information not normally collected by the web server can only be recorded by modifying the URL.
• The page tagging service manages the process of assigning cookies to visitors; with logfile analysis, the server has to be configured to do this.
• Page tagging is available to companies who do not run their own web servers.