What is a favicon?
A favicon (short for favorites icon), also known as a website icon, shortcut icon, url icon, or bookmark icon is a 16×16, 32×32 or 64×64 pixel square icon associated with a particular website or webpage.
A web designer can create such an icon and install it into a website (or webpage) by several means, and most graphical web browsers will then make use of it. Browsers that provide favicon support typically display a page's favicon in the browser's address bar and next to the page's name in a list of bookmarks. Browsers that support a tabbed document interface typically show a page's favicon next to the page's title on the tab. Some programs allow the user to select an icon of his own from the hard drive and associate it with a website.
How to setup
Here is the instruction to setup a favicon for your PrestaShop.
You can use some free online tools or service like http://www.favicongenerator.com/.
Event Paint which is Windows included tool is able to do that. Just save it with extention "ico".
Make sure you the size is 16 x 16 pixels
You are done.
See sample at:
Please also note:
1. It takes for a while for your favicon to show up on your browsers. (like 1 hour?)
2. It is better to clear your browser's cache to force your browser to download your new favicon.