What is a Favicon?
A favicon, short for favourite icon, is a small square icon that represents your brand. It is shown in the browser tab when you visit a website and also within Google's mobile search results.
Having a favicon that is consistent with your main logo and colours provides an easy way for searchers and website visitors to recognise your brand at a glance.
Favicon Criteria for Mobile Search
When creating a favicon for mobile search results there are a few additional criteria to be aware of:
Your favicon must be hosted on your own domain e.g. if your homepage is example.com then your favicon could be hosted at example.com/favicon.ico
Your favicon should be a multiple of 48px square. This one can easily catch you out because a favicon that shows in the browser will work at almost any size. Google, however, recommend a minimum size of 48x48px or any increment that is a multiple of 48px e.g.
Testing Mobile Favicons
This might appear "smack you in the face obvious" but the easiest way to check your favicon is showing in mobile search results is to search in Google using your smartphone.
That said you can also check Google's mobile search results from your laptop or desktop computer. The easiest way to do this is to use the Inspector in Chrome, Ctrl Shift I. Then Toggle Device Toolbar, Ctrl Shift M.