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 website. This type of a log features raw info about the way the web server has addressed requests in different situations. An error message might appear if, for instance, a link leads to a website or a file that is not on the server, if the code on a certain 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 and many others. The info in the error log offers the IP of the visitor, what error message appeared and the root cause for the web server to show it, the full path to the file that generated the error and the precise time of the event. Having this info will help you determine if any part of your website has an issue, which you may then fix. For that reason, your site visitors will have a better experience and you'll boost the website for optimum performance.