In this first issue of The SEO Letter, I am sharing a tip that is not much discussed but is important: Favicon optimization.
Google now displays the favicons in all the listings in search results, which can affect the CTR (click-through rate) if they're properly visible or not visible.
So you should use a good favicon on your site so that users can refer to your brand in SERPs.
Also, keep your favicons consistent across your site — for consistent brand perception.
If, by any chance, your site's favicon isn't showing up in Google search results, make sure both the favicon file and the homepage is crawlable by Google, the favicon file is a multiple of 48px square, and the favicon is a representation of your website's brand.
You can also refer to Google's guidelines on this.