An error log is a listing of the error messages and warnings which appeared for one reason or another while your visitors were browsing your site. This sort of a log features raw information about the way the web server has handled requests in various situations. An error message might appear if, for instance, a link leads to a site or a file that isn't on the web server, if the code on a particular page can't be processed, if anyone is trying to access the site or its back office via an IP address which is blocked by an .htaccess rule and so forth. The information within the error log includes the IP of the visitor, what error message appeared and the basis for the web server to display it, the whole path to the file which induced the error and the precise time of the event. Having this information will allow you to find out if any part of your site has a problem, which you could then fix. As a result, your site visitors will have a better experience and you'll optimize the Internet site for maximum performance.