How accurate is HTML5 geolocation?

HTML5 geolocation is more accurate than other tracking methods, like IP geolocation. However, it is best used for devices that feature a GPS, like a smartphone. While it can work for desktops, HTML5 is best suited for GPS devices. It is also important to note that Geolocation API is only supported by certain versions of the browser, like Google Chrome 5.0 and Mozilla Firefox 3.5.