An error log is a list of the error messages and warnings which appeared for one reason or another while your visitors were surfing around your website. Such a log provides raw information on the way the web server has handled requests in different situations. An error message may appear if, for example, a link leads to a webpage or a file that isn't on the web server, if the code on a particular page can't be processed, if any individual is trying to access the website or its back office through an IP address that's blocked by an .htaccess rule and many others. The information within the error log includes the IP address of the visitor, what error message showed up and the basis for the web server to show it, the full path to the file which caused the error and the exact time of the event. Having this info will enable you to figure out if any part of your site has an issue, that you can then deal with. As a result, your website visitors will have a better experience and you will optimize the Internet site for maximum performance.