Favicons: You’re Doing Them Wrong

Cyan-Light — Sun, 04 Jan 2009 20:33:00 +0000

Favicons have been with us from the start of the Internet as we know it, but the vast majority of web authors are still using them wrong. Why? Our little friend the MIME is here to help.

Mime Types and the Internet

Officially Internet media type nowadays, the Mime type originated as a way of signifying additional files on email served via SMTP. Mime types are made up of two pieces of information: a type and then a subtype. Additionally, a charset parameter may inform of the character set of the file.

You will have used these before: when writing a HTML document, you’ve always written something like this:

The Mime type is the text/html bit.

Usually, when a web author links to a favicon on his page, he might define it as image/x-icon.

While this is strictly correct HTML, it is telling the browser that it is linking to a nonstandard, ICO image.

The problem is that ICO images have been standardized and registered with the IANA for 6 years, and you really have to start paying them their dues.

The correct Mime type for ICO images is image/vnd.microsoft.icon. Thus, a fully correct rendition of a link to a favicon would be something like this:

Respect to the Mimes, people!

Cyan-Light Industries » common errors

Favicons: You’re Doing Them Wrong

Mime Types and the Internet