Did you know that your computer, your iPad, and even your smartphone can tell another person quite a bit about where you are? In fact, Google's geolocation software is so accurate that it can often determine what side of campus we're accessing Google Maps from, using the school network. Most internet-based geolocation software uses internet protocol (IP) addresses which are assigned by your internet service provider (ISP) and can be easily read and analyzed by server-side software. This is legal, and in fact encouraged by banks and law enforcement, as in the first case it helps to prevent fraud, and in the second case it helps to track down criminals. Organizations providing location-based content often utilize this software to return the most helpful content to the user, such as Google's Maps Search function, which returns the "closest" options.

Read more about Geolocation Software on Wikipedia!
Learn about Geolocation by visiting these sites:
Geolocation 101: How It Works, the Apps, and Your Privacy - PCWorld
Geolocation by IP Address | Linux Journal
Geolocation on Wikipedia