CraigyBabyJ guide
Favicon files and sizes: what to generate for a modern website
A favicon set is more than the tiny icon in a browser tab. Modern sites use different files for browser tabs, bookmarks, search results, pinned shortcuts and mobile homescreen icons.
The short version
Keep a simple square source image with transparent padding, then generate favicon.ico, 16x16 and 32x32 PNG icons, a 180x180 Apple touch icon and larger Android icons. That gives browsers and devices a sensible file for each place the icon appears.
Why favicon.ico still matters
Modern browsers can use PNG icons, but favicon.ico is still a useful fallback because one ICO file can contain several bitmap sizes. It is especially helpful for older software, Windows shortcuts and places where the browser asks for the classic root favicon.
What to check before uploading
Open the smallest generated icons before publishing. If the logo uses thin text, gradients or fine outlines, the 16x16 version may turn into a blur. A bold mark with a little edge padding usually works better than a full wordmark.
Useful tools for this job
Use these tools when you are ready to try the workflow on your own files.