I am trying to do a very simple preliminary exercise to setting up a website which is creating a favicon.
This is the code I am using:
With the introduction of (i|android|windows)phones, things have changed, and to get a correct and complete solution that works on any device is really time-consuming.
You can have a peek at https://realfavicongenerator.net/favicon_compatibility or http://caniuse.com/#search=favicon to get an idea on the best way to get something that works on any device.
You should have a look at http://realfavicongenerator.net/ to automate a large part of this work, and probably at https://github.com/audreyr/favicon-cheat-sheet to understand how it works (even if this latter resource hasn't been updated in a loooong time).
One complete solution requires to add to you header the following (with the corresponding pictures and files, of course) :
In June 2016, RealFaviconGenerator claimed that the following 5 lines of code were supporting as many devices as the previous 18 lines: