PALO ALTO, CALIFORNIA (CNN) – Facebook Places, just recently launched by the social network giant Facebook and slowly rolling out to all US users and later to the rest of the world. What is this all about?, so you may ask yourself. It’s a new “hot” trend to share your location with your social network friends (and the world, if your privacy settings flawed). “If Facebook thinks that location is a good idea, then we are on to something,” Foursquare, a pioneer in location-based social networking, CEO Dennis Crowley said to press.

Facebook pitch the value of Places for enhancing everyday life and cite examples of where Facebook Places can help connect friends or tell stories about what others did at popular places.

Facebook Places, like existing location-based apps Foursquare and Gowalla, use GPS information from your mobile phone, so people can “check in” on their smart phones, letting friends know where they are and what they’re up to. It’s most probably useful to young and socially active people.

Say you’re at a bar, restaurant, coffeehouse or club. The idea is that if one of your friends sees your check-in and is nearby, they can swing by and hang out with you.

You can also leave comments and tips for friends to see. If you like a particular dish at a restaurant, or had bad service there, you can post that info with your check-in and notify your friends.

The app, using GPS, also will identify other hot spots in your area, ..and the comments people have left about those places, so you could discover new hangouts and social possibilities.

Who can use it? People who have the latest Facebook app on their smartphones (currently iPhone, later followed by Android and Blackberry), or if they visit FB’s touch screen version at touch.facebook.com in some enabled places (mostly in U.S.). Currently, iPhone users will see the Places option when they download the latest update to the Facebook app.

If you don’t use Facebook on your phone, Places probably won’t change your Facebook use in any way – except that your news feed may start showing when your friends check in.

What about privacy? Many people are expressing concerns that the app will take away their privacy by letting others (including, in the scariest scenarios, stalkers or crooks) – know their location. Some important facts about that:

• If you don’t choose to check in, your location isn’t revealed. It seems basic, but there appears to be a lot of confusion about this. Nothing about Facebook Places (and Foursquare and other mobile apps, for that matter) tells people where you are if you don’t choose to tell them.
• The default setting for Facebook Places only sends location alerts to your Facebook friends. There are ways to change that to tell more, or fewer, people. But as is, no one you haven’t approved as a friend can see what you post.
• When you’re with a group, Facebook friends can check you in along with themselves to let people know what kind of group is hanging out. But Facebook says they’ll only be able to do so if you have checked yourself in at the same place. In other words, nobody can post your “check-in” location without your approval (although as always, they could still mention your whereabouts in a status update).
  Important detail: If you’re not comfortable with all your friends’ friends seeing where you are, you can adjust your settings to prevent that, too. Otherwise, if you both check in somewhere, their friends can see your location.
• Your check-ins likely will appear in the activity stream on the Facebook Places page for your location — unless you change your settings. So other people who were nearby might be able to see you as well as your friends.

For those of you who are looking to precisely control how Facebook Places share your check-ins information, you can find it here.

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