Geolocation 101: How It Works, the Apps, and Your Privacy

Facebook wants to know “What’s on your mind?” Twitter asks “What’s happening?” But that’s getting old already. The burning question for the next wave of social networking is “Where are you?”--and services like Foursquare, Gowalla, Brightkite, and Loopt want you to use your smartphone to answer it.

The technology at the heart of this trend is called geolocation; and with a GPS-enabled smartphone such as the Apple iPhone, Google Nexus One, or RIM BlackBerry, you can use it to let your friends know where you are, or to find places recommended by people you know, or to check in remotely at clubs, bars, and restaurants. Regardless of privacy concerns (which I'll look at later in this article), it looks as though nothing will stop geolocation.

How It Works

Typically, geolocation apps do two things: They report your location to other users, and they associate real-world locations (such as restaurants and events) to your location. Geolocation apps that run on mobile devices provide a richer experience than those that run on desktop PCs because the relevant data you send and receive changes as your location changes.

Smartphones today have a GPS chip inside, and the chip uses satellite data to calculate your exact position (usually when you're outside and the sky is clear), which services such as Google Maps can then map. When a GPS signal is unavailable, geolocation apps can use information from cell towers to triangulate your approximate position, a method that isn't as accurate as GPS but is has greatly improveds in recent years. Some geolocation systems use GPS and cell site triangulation (and in some instances, local Wi-Fi networks) in combination to zero in on the location of a device; this arrangement is called Assisted GPS (A-GPS).

As long as the sky is fairly clear, the geolocation app on your phone can ascertain your position reasonably accurately. Indoors, however, it’s less accurate, and in locales where storefronts are in very close proximity, you may have to select your location manually from within the app interface.Eventually, though, more-advanced A-GPS systems should increase the accuracy of geolocation positioning inside buildings.

The First Wave of Apps

Several start-up companies offer geolocation services--and some, such as Foursquare, reach hundreds of thousands of users. Not only do these services let you share your location with your friends, but they also bring a social gaming element to the table. Let’s have a look at some of them.

Foursquare on an Android phone shows your profile info, together with badges that you've earned and the last place you checked in to. Image: Foursquare
Foursquare works with iPhone, Android, BlackBerry, and Palm (WebOS) phones. If no app exists for your smartphone, you can always use the Foursquare mobile Website instead. Foursquare refers to announcing your location--and thus telling your friends where they can find you--as “checking in."

You can check in to cafés, bars, restaurants, parks, offices, and pretty much anyplace else. Once your friends know where you are, they can recommend places for you to go or things for you to do and see nearby. To keep it fun, the service gives you points for each check-in; and in time you can earn various badges tracking your progress toward Foursquare elitehood.

Even cooler, if the service recognizes you as the mayor of a location (by virtue of your having visited that place more frequently than anyone else), you are in for some freebies. Foursquare has a massive list of places all over the world that offer special discounts and free drinks to their mayors, or to anyone who has registered a certain number of check-ins at their site.

Gowalla on a Palm Pre shows the top 10 users who've checked in at a certain location, together with the number of check-ins by each. Image: Gowalla
Gowalla, like Foursquare, works with the iPhone, Android, Palm (WebOS), and BlackBerry (on Bold, Curve, and Storm phones) platforms. The service has a huge database of locations curated by users, and you and other participants can trade virtual items that you've collect. Gowalla also has worked out several advertising partnerships that enable you exchange virtual goods for their real-life counterparts for free.

Gowalla recently added a trips feature (iPhone-only at the moment; Android and WebOS versions coming soon) that lets users recommend up to 20 locations that they like to other Gowalla enthusiasts. Your friends can then complete the trips, such as city tours or bar crawls.

Brightkite on a Nokia Symbian phone shows a list of nearby friends and their statuses. Image: Brightkite.
Brightkite works with iPhone, Android, Palm, Nokia, and BlackBerry smartphones. This service lets you establish two kinds of social connections: fans (Twitter-like followers) and Facebook-like friends. Aside from sharing your location, you can post short messages that your friends or fans can respond to with a thumb up or thumb down.

Brightkite has excellent privacy controls that let you share individual posts with everyone or with friends only; you can also cross-post on Facebook, Flickr, and Twitter. Like Foursquare and Gowalla, Brightkite uses the check-in system for bars, clubs, museum, and the like, and it finds your location automatically.

Loopt on an iPhone identifies places that are near you and lets you select the correct option and check in. Image: Loopt
Loopt, which combines geolocation with social networking, is available for the iPhone, BlackBerry, Android, and many other phones (full list). Like other services, Loopt invites you to check in to locations and share what you're doing with Facebook and Twitter friends, next to your own network of Loopt friends.

Loopt also provides an event directory called Pulse, where you can browse various listings categories (such as movies, gigs, and shows) for things going on near you--and afterward leave ratings and tips. Freebies and special offers are available too, indexed from nearby retailers.

For comprehensive coverage of the Android ecosystem, visit Greenbot.com.

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