Even if you didn’t know the official name, you have most certainly one.  A favicon is the small square image, usually 16 x 16 pixels, used to show a graphical representation of the website you’re visiting.  The word itself was derived from “favorite” and “icon”. The use of the word became popular due to the feature of bookmarking favorites which dates back to Microsoft’s Internet Explorer 5. 

• A small square image used by web browsers to show a graphical representation of the site being visited.
• Improves User Experience.
• Raises brand awareness.