First introduced in 1999 by Microsoft in their Internet Explorer browser platform, favicons have undergone little change until recently. A small graphic file, usually packaged into a .ico file that is displayed in or next to the browser address bar. Through the evolution of browsers this little graphic has taken on much more importance in our daily web surfing lives. Providing users with instant brand recognition, a favicon can be an immediate and lasting reminder of your company or site. Originally packaged as a single small 16px x 16px file, favicons have come begun to change with the emergence of new technology and display resolution. Now it is common to have multiple image sizes packaged into a single .ico file so the browser can pick the one best suited to the device display. An excellent read on the subject was written by Jonathan T. Neal located here: Understand the Favicon
Though small in size, the impact of a favicon is one that should not be overlooked. Grab a copy Icon Slate
and get started.