A favicon is an icon associated to a website or web page, it is also called website icon or page icon. There are several ways to implement it but the most traditional one is placing a favicon.ico image file. This image is going to be displayed in the web browser tool bar and bookmarks.

Favicons are not only important for marketing and branding proposes but also for usability:

- Favicons help the user to identify pages among the web browser tabs

- They help to visually identify bookmarks

- Because of the previous two points, they make users to save time and to make internet browsing a more comfortable experience

Tabs

Notice how easy it is to identify tabs if they have favicons:

Bookmarks

Users can easily search through bookmarks that have favicons:

The Branding Problem

Sometimes using favicons requires to make a balance between branding and usability. In the following example Google uses the same favicon for all its services. This has a positive and a negative effect: on one side different services benefit from the main Google brand if they share the same favicon, on the other side it makes difficult to differentiate different pages and services from the same company.  This a valid approach but using several favicons for different services of the same company/website could improve usability.

The Google favicon among different services: