Creating a Favicon
These days, all major browsers accept images in PNG format as a favicon. The image should have a square aspect ratio (192px × 192px is a good size). It's a good idea to name the file
favicon.png and place it in the root directory of the website.
Also note that PNG images support transparency, so you can create an image that is circular or other non-rectangular and the background will show through.
Using a Favicon on a Site
The most reliable way to let the browser know about a favicon is to link it in the
head of each html document, similar to how we link to CSS files: