Favicons are the tiny icons associated with a website that display on most browsers in the tab area of the browser window. They may also display when the website is favorited or added as a bookmark.
WordPress has a feature in the Appearance menu that is explicitly for favicons – the Site Icon. Per the description, the Site Icon needs to be 512px x 512px.
Below are two templates for creation of a favicon – one for Adobe Illustrator and one for Adobe Photoshop. Please use one of these templates when creating the favicon for the site.