If you are asking what a favicon is this is how Wikipedia defines them:
A favicon /ˈfæv.ɪˌkɒn/ (short for favorite icon), also known as a shortcut icon, website icon, tab icon, URL icon, or bookmark icon, is a file containing one or more small icons, associated with a particular website or web page.
Safari recently began (I am using Safari 12.0.3 running on macOS 10.13.6) to natively support favicons. Favicon display must be enabled before you will see them in your browser tabs. To enable them on your Mac do:
- Open the Safari App
Click on Safari in the top left corner, then select Preferences from the drop-down menu
- Select ‘Tabs’
Click on the Check Box next to “Show website icons in tabs”
- Close the Preference window
You are all set now. Favicons will show up in the browser tab for each site you visit that has favicons implemented.
So now when I open tabs in Safari with pages from the Wikipedia, Apple, and Stuff You Missed in History Class sites respectively, you see the little icons in the tabs. Having favicons enabled isn’t a big deal, but it does let you identify at a glance the source of each tab.
See my other Mac and macOS articles