1) For serving you a language version it's generally IP-based. The services like MaxMind update their DBs regularly because IP<>country assignments are not cons

1) For serving you a language version it's generally IP-based. The services like MaxMind update their DBs regularly because IP<>country assignments are not constant. (It's a bit of show in case of mobile IPs, like I'm in south of France and sometimes Google thinks I'm in Paris etc.). Some users of those geoip services might have stale data if they don't update often. I remember reading on HN about a guy from Switzerland whose IP is regularly changed in those DBs from "Switzerland, $French_speaking_region" to "Switzerland, $German_speaking_region" back and forth, so each month he sees local Swiss websites in a different language! 2) For getting your precise location, apart from GPS data, they also have a giant DB of wifi access points' names collected by passively sniffing wifis on a few billion Android devices (and other devices with Google software) all over the world; by intersecting this with names of wifis visible from your machine, they can assess your location even if your device has no GPS device built-in. 3) On mobile phones, your location is often taken based on the mobile network you're on. If you go abroad and connect in roaming, from network perspective you might be seen as being in the capital of your country, and have IP from your country, even if you're not there physically. 4) Some companies just use the CC number you signed with as the indicator of your country, regardless where you are physically. TL;DR; it's a mess