Note, however, that most modern browsers replaced the favicon from the address bar by an image indicating whether or not the website is using HTTPS .

Usually, a favicon is 16 x 16 pixels in size and stored in the GIF , PNG , or ICO file format.

They are used to improve user experience and enforce brand consistency. When a familiar icon is seen in the browser's address bar, for example, it helps users know they are in the right place.