If you run an Apache2 server then you have no doubt seen the following error messages a thousand times in your error.log file:
File does not exist: /var/www/robots.txt
File does not exist: /var/www/favicon.ico
As you know by now not having a favicon.ico file web browsers will requesting it each time. But you can tell Apache2 not to log the event as a mistake message.
You will still see the request in the access.log, but at least you will have a cleaner error.log file.