Jonathan T. Neal | Understand the Favicon

When Alec Rust asked the HTML5 Boilerplate project to switch to a HiDPI favicon, I realized how little I knew about favorite icons, touch icons, and tile icons. When I decided to dive in a little deeper, things got interesting. Since they were first introduced by Internet Explorer in 1999, almost nothing about favicons has changed. They have almost-always been ICO files, either nested in the root of the domain as /favicon.ico, or organized by a CMS into a theme or images directory and displayed with: