A favicon is a small, square image that is used as an icon on websites and web pages.
A favicon (; short for favourite icon), also known as a shortcut icon, website icon, tab icon, URL icon, or bookmark icon, is a file containing one or more small icons, associated with a particular website or web page.
A web designer can create such an icon and upload it to a website (or web page) by several means, and 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 (sometimes in the history as well) and next to the page's name in a list of bookmarks.
A favicon is important because it gives a web page or website a unique identity, and it also makes it easier for users to recognize a page or site they have visited before.
Additionally, favicons can be used to indicate when a page is loading slowly, as the favicon will usually start to blink or turn grey when the page is taking longer than normal to load.