Favicons are the 16 pixel square images that precede the website title in browser window tabs. When it comes to branding thumbnail images (of which, favicons are the smallest), few logos can be represented in their entirety, so we recommend a piece of the logo, or simply, the branded color(s).
To make a favicon, create a simple square image that incorporates some aspect of the brand. Import the image into an online favicon generator. Choose the multiple sizes for the .ico, which includes 16, 32 and 48 pixel images which will be included in the file. It may take a few tries to get a look you like. Place the favicon.ico file in the top level (root directory) of your website, and you’re done.
Favicons are hilariously complicated, and new devices are beginning to demand a variety of icon sizes, but for now, this method works in most cases.