Favicon can be your logo or other picture that will stand out your Joomla website from others. After Joomla template installation there will be standard favicon, and you will need to know the answer on question How in Joomla to change favicon Favicon creates a visual perception with your site, just like logo, so you will totally need to upload your custom favicon. Follow this simple steps and you will know how to change favicon on your Joomla website:
After installation of Joomla template you will see the small icon on the top left corner of the window, it is called favicon.
You can use professional design tools such as Photoshop, or try simple favicon creator http://antifavicon.com/
Convert favicon into .ico format with a help of online tools.
Copy converted favicon with a .ico extension to /joomla/templates/<your template> folder and name in favicon.ico
Open your browser and favicon must be changed after refreshing, if not, just clear your cache and all will be fine.
Check other Joomla tutorials and get more knowledge.