For web page icon on iPhone or iPad, use the Apple Touch Icon or apple-touch-icon.png file. This icon is used when someone adds your web page as a bookmark.
For multiple icons with different device resolutions like iPhone or iPad, add sizes attribute to each link element as follows −
<link rel = "apple-touch-icon" href = "touch-icon-iphone.png">
Set size
<link rel = "apple-touch-icon" sizes = "160x160" href = "touch-icon-ipad.png"> <link rel = "apple-touch-icon" sizes = "170x170" href = "touch-icon-iphone-retina.png"> <link rel = "apple-touch-icon" sizes = "180x180" href = "touch-icon-ipad-retina.png">
The icon with the appropriate size for the device is used.