iOS Specifying Web Clip icon

Developer can add web application or web link to home screen. These links are represented by icon are called web clips. 

Below are few guidelines 

1. To specify an icon for the entire web site, place an icon in PNG format in the root document folder called apple-touch-icon.png 

2. To specify an icon for single page, add link element in the web page. This also overrides the website icon 

3. To specify multiple icons for different device resolutions - for e.g. for support for both iPad and iPhone devices - add sizes attribute to each link element as follows 

"apple-touch-icon" sizes="76x76" href="touch-icon-ipad.png"

"apple-touch-icon" sizes="120x120" href="touch-icon-iphone-retina.png"

"apple-touch-icon" sizes="152x152" href="touch-icon-ipad-retina.png"

References:

https://developer.apple.com/library/ios/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html#//apple_ref/doc/uid/TP40002051-CH3-SW4