An error log is a list of the error messages and warnings that displayed for one reason or another while your visitors were looking through your website. Such a log features raw information about the way the hosting server has handled requests a number of situations. An error message could appear if, for instance, a link leads to a site or a file that isn't on the hosting server, if the code on a specific page can't be processed, if anyone is trying to access the website or its back office using an IP address which is blocked by an .htaccess rule and so on. The info in the error log features the IP of the site visitor, what error message showed up and the cause for the server to display it, the full path to the file that triggered the error and the specific time of the event. Having this info will allow you to learn if any part of your website has an issue, which you could then resolve. Consequently, your website visitors will have a better experience and you may optimize the website for optimum performance.