Android
When Android devices cannot locate a suitable shortcut icon, it will add a tile with the first letter of your website’s url to the homescreen. This is a missed branding opportunity, where your logo could be appearing.
from Samsung Tab 4 Home Screen
How to fix Android Shortcuts:
<link rel="icon" sizes="192x192" href="http://[yourwebsite]/192x192 filename.png"/>
<link rel="manifest" href="http://[your website]/manifest.json"/>
iPhone
When iPhones cannot locate a suitable shortcut icon, they will add a miniature image of your website to the homescreen. This is a missed logo opportunity, and can be confusing to the user.
How to fix iPhone Shortcuts:
<link rel="apple-touch-icon" sizes="180x180" href="http://[yourwebsite]/180by180.png"/>
<link rel="apple-touch-icon" href="http://[yourwebsite]/apple-touch-icon.png"/>
Windows
Windows can pin your Website’s logo to the taskbar. If a suitable shortcut icon cannot be found, Windows will use the Internet Explorer logo for the link. This is a missed branding opportunity for your organization.
Windows 7 – IE7 pinned shortcut to Taskbar
How to fix Windows Tiles and Shortcuts:
<meta name="msapplication-tooltip" content="Your Website Name"/>
<meta name="msapplication-starturl" content="./"/>
<meta name="msapplication-TileImage" content=" http://[yourwebsite]/144x144.png"/>
<meta name="msapplication-TileColor" content="#000000"/>
<meta name="msapplication-square70x70logo" content="http://[yourwebsite]/128x128.png"/>
<meta name="msapplication-square150x150logo" content="http://[yourwebsite]/270x270.png"/>
<meta name="msapplication-wide310x150logo" content="http://[yourwebsite]/558x270.png"/>
<meta name="msapplication-square310x310logo" content="http://[yourwebsite]/558x558.png"/>
<link rel="shortcut icon" href="http://[yourwebsite]/favicon.ico"/>
<link rel="icon" href="http://[yourwebsite]/favicon.ico"/>
Favicon Recommendations
Website Shortcut Recommendations
Chrome
Chrome for Windows and Chrome OS both allow for website url logos to be Added to the Shelf, or pinned to the Taskbar. When appropriate icons cannot be found, a letter tile is used in place of the logo. This can easily be corrected.
Chrome OS – Chrome Added to Shelf
Windows 7 – Chrome added shortcut to Taskbar
How to fix Chrome Shortcuts:
<link rel="shortcut icon" href="http://[yourwebsite]/favicon.ico"/>
Favicon Recommendations
Website Shortcut Recommendations