A favicon is a small image that resides in your browser’s ‘tabs’, so you can identify the brand at a glance. Favicons may also display in bookmark lists too.
Favicons can also be used in lists of bookmarks in web browsers and feed aggregators.
Here are examples, outlined in purple, of favicons appearing in the browser:
You can see that it is common to use a smaller version of your logo for your favicon to keep consistency throughout your site and branding.
Flavicon's can be added by navigating the following steps from your Shopify dashboard:
Online Store → Themes → Customise
4. Choose “Select image”
Upload your image and this will be automatically be scaled down to 32 x 32px.