<!-- Place favicon.ico and apple-touch-icon.png in the root of your domain and delete these references -->
<link rel="shortcut icon" href="/favicon.ico">
<link rel="apple-touch-icon" href="/touch-icon-iphone.png">
<link rel="apple-touch-icon" sizes="72x72" href="touch-icon-ipad.png" />
<link rel="apple-touch-icon" sizes="114x114" href="touch-icon-iphone4.png" />
<link rel="apple-touch-icon-precomposed" href="/touch-icon-android.png"/>

http://www.cappellin.net/2010/12/favicon-and-apple-icons.html

A favicon (short for favorites icon), also known as a shortcut icon, website icon, URL icon, or bookmark icon is a 16×16 or 32×32 pixel square icon associated with a particular website or webpage. The interesting bit here is the apple-touch-icon which is used if you save a bookmark to your home screen on an apple touch device such as an iPad or iPhone. Interestingly enough, android also supports its usage. The apple-touch-icon default size is 57px by 57px. As the comment says, if your icons are in the root of your domain, these links aren’t required.

Favicon and Apple icons

iphone, android

HTML