An access log includes a record of all the files that have been requested by the visitors while browsing your site. The list is detailed, so if you have a page with 2 embedded images, for instance, all of the three files will be in the log, not only the page. An access log normally contains the date, the OS, the browser and the IP address for each file in human-readable form, so you can get an idea about the most popular files on your Internet site. The log, that's also commonly referred to as "raw data", is an addition to the web data which you normally get with a hosting account, not a replacement. One example why you may require such a log is if you intend to use some software on your personal computer to prepare a report about the website’s overall performance, but you don't want to use the regular graphs and tables which come with the server-generated web stats.