For Visualforce pages,  you can refer to [this knowledge article][1]

For Lightning communities, you can refer to the [community templates documentation][2]

Important note for troubleshooting favicon issues:

 1. Ensure that the favicon is referenced properly.
 2. Using your browsers developer tools, under the network tab, validate the above.
 3. Include this information in your post.

Reference on using the [network tab][3] for Chrome.


  [1]: https://help.salesforce.com/articleView?id=000167021&type=1
  [2]: https://resources.docs.salesforce.com/latest/latest/en-us/sfdc/pdf/community_templates.pdf
  [3]: https://developers.google.com/web/tools/chrome-devtools/network-performance/reference