When a person or script unsuccessfully attempts to access a section of your website, or when a page is loaded where a picture cannot be found, an error will be returned to the server. These error messages are stored in a log called Error Logs and are very handy for debugging your website and tracing any unseen errors.
The most common error message is File Does Not Exist. This occurs when someone tries to access a page or file on your website that does not exist – it may have been deleted or they may have used an incorrect URL.
For reference purposes, the Error Logs also display the IP address of the computer that tried to access the file that produced the error.