A favicon is a small website icon. Just like software programs can have custom file icons, websites can have custom icons that show up in a web browser. The term "favicon" is short for "favorites icon," since it is saved with any bookmarks or "favorites" you create. However, modern web browsers also display favicons whenever you visit a website. In some browsers, the favicon appears to the left of the URL, while other browsers display the favicon in the window tab, next to the page title.
The standard way to develop a favicon is to create an .ICO file with an image that represents the website. It should contain a 16x16 pixel image, but may also include a 32x32 icon, which can be displayed on Hi-DPI screens. The file must be named "favicon.ico" and uploaded to the root directory of the associated website. While favicons should be saved in the Windows ICO format, most web browsers (besides Internet Explorer) will display favicons saved as .GIF, .JPG, or .PNG files.
Updated: October 1, 2013