An access log is a text file containing a thorough list of all of the files accessed by your site visitors. All of the files which were requested in one way or another will be included, so when you have a PHP script program and a visitor opens just the home page, for instance, you might find many files inside the log. The reason is that there are things on the home page that are embedded - parts of other webpages, pics, etc. All these files shall be listed inside the access log, so that you can get a detailed picture of the way your Internet site performs. The info is in plain text format, so the logs are frequently called "raw data" as well. An access log contains the name of each requested file, the path to it, the date it was accessed, in addition to the user’s IP address, web browser and OS. Additional information, like the referrer site, is usually provided as well. A log file can be processed by various desktop applications for statistical purposes as an addition to the web stats provided by your web server.