The favicon is the icon the you can see on your browser's tab when you are on your site.
It is like an avatar for your site, that anyone can see. When you create your site with Swite, the favicon is set by default with the Swite logo. But if you want you can always change it.
To do so, enter your site and click on Site Settings.
Here you'll find a field called Icon (Favicon) and by clicking on Upload Icon you'll be able to upload a customized image.
Changes on this page are saved automatically. If you would like to go back to the default icon just click on Default Icon.