Classic favicon for desktop browsers
Drop a favicon.ico file in the root directory of your web site. It does not need to be declared and it is expected to contain 16x16, 32x32 and 48x48 pictures.
Modern browsers will also look for PNG icons. You can address most cases with:
iOS
If you combine iOS 6 and iOS 7 sizes, iPad and iPhone, and Retina and non-Retina, that gives you 8 Apple touch icons:
Android
Android Chrome uses the Apple touch icon. But it also documents a 196x196 PNG icon that will replace the touch icon... someday. So:
Windows 8.0 tile picture
Windows 8.1 tile pictures
or use a browserconfig.xml dropped in the root of your web site (or declared in the head section), with the following content:
#da532c
The other guys
What about Google TV, Opera Speed dials and others? They expect PNG icons:
(...)
Generate these pictures and HTML code
You can generate all these pictures and HTML code at once. Full disclosure: I'm the author of this site.
