Some people are concerned that there are security risks when using a favicon, and while there have been a few exploits they have been fixed right away and the primary concerns that people have with favicons have turned out to be non-existent or less serious than they seemed.
Learn about the favicon or favorites icon used to decorate your site in the bookmarks and tab bar of browsers.
Not all browsers support favicon, make sure the one your testing with does.
Once you have a favicon, where will it display when you post it.
favicon.ico not found in error log