A W3C log is an access log for Web servers in which text files are generated containing data about each access request, including the source Internet Protocol ( IP ) address, the HTTP version, the browser type, the referrer page, and the timestamp. The format was developed by the World Wide Web Consortium ( W3C ), an organization that promotes standards for the evolution of the Web.
If a Web page contains multiple elements (which is usually the case) and it is accessed by an Internet user, the W3C log for that event creates a separate record for each element of the page. Because of this, W3C log files tend to be large and arcane. For example, if a Web a page consists of multiple image files, a wave file, and a text file, and the page is visited by a single Internet user one time, then several access records will be generated in the W3C log for that event. This can make useful data difficult to extract, and can also give the Web site administrator a distorted notion of the number of visits the page actually receives. This is one reason why application logging is often used in addition to W3C logging.