While working with SharePoint customization, I got a requirement to change the favicon image. I have never changed favicon image before working on SharePoint 2007 and SharePoint 2013. By default Microsoft people will have following favicon images for SharePoint 2010 and SharePoint 2013.
By default it will be located in C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\IMAGES and C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\TEMPLATE\IMAGES folders.
To Change the favicon Images open SharePoint Designer and Select the master page to set custom favicon Image. Add favicon image in default favicon location (C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\TEMPLATE\IMAGES in SharePoint 2013 or C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\IMAGES in SharePoint 2010). In the master page check for <SharePoint:SPShortcutIcon tag, Change the image URL to favicon image to set.
Save and publish the master page and reset IIS. Finally we can see the updated favicon image as shown below.
In SharePoint 2013, we have to change the Icon URL in html file. After changing the url in html page master page will automatically refer the same URL.
Sometimes we cannot see the favicon image immediately. In internet explorer may hold the cache items. For that situations, clear the cache and reload the page.