Unlike IP-based geolocation (approximate, at the city level), HTML5 geolocation uses your device's GPS or Wi-Fi to locate you much more precisely. It requires your explicit permission and only works over a secure connection (HTTPS).

IP vs. HTML5 geolocation: what's the difference?

IP-based geolocation (used on the home page) generally gets the right city or region, but remains an estimate based on a network block database. The HTML5 geolocation on this page, however, uses your device's GPS or Wi-Fi to locate you within a few metres — far more precise, but only for your own location, with your explicit permission.