An error log is a listing of the error messages and warnings which displayed for one reason or another while your visitors were browsing your site. This kind of a log features raw information about the way the 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 is not on the server, if the code on a specific page cannot be processed, if someone is trying to access the website or its back office through an IP address that's blocked by an .htaccess rule etc. The data within the error log features the IP of the visitor, what error message showed up and the root cause for the server to show it, the entire path to the file that triggered the error and the precise time of the event. Having this data will enable you to figure out if any part of your Internet site has an issue, that you can then take care of. For that reason, your website visitors will have a better experience and you'll optimize the site for best performance.