This file exists to keep track of the sytnax for specifying favicons.
Favicons appeared without much specification, and there appears to be confusion over how to use them. They first showed up in Internet Explorer; if you bookmark a web page, then internet explorer grabs an icon from the website to use as that sites icon in your bookmark list.
The behavior grew, and now there are two standards. In Internet Explorer, you can put "favicon.ico" file at the top directory of your web server. In theory you can also put a <rel link="shortcut icon" src="…" type ="…"> tag into the page header. In Netscape/Mozilla/Firefox, you put a <rel link="icon" src="…" type="…"> tag into the header.
I don't know if relative or absolute URLs are needed...
Type stuff. Or make words italic.