Know that Face? Facebook Does.

No doubt about it, sharing pictures on Facebook is a major pastime for teens. And if they're careful with what they post and use privacy settings (a big if!), enjoying friends' pics is part of the fun of social networking. But Facebook's new face-recognition software can now automatically recognize people in photos -- and add their name to the picture -- dramatically increasing the number of places that your teen's photos can pop up.

How it Works

Called Tag Suggestions, the program digitally scans the faces in photos and suggests who they are so that you can tag them. The company claims that this feature makes it a lot easier for users to label and share photos. But it also makes it a lot easier for teens' online identity to get away from them.

[[See Protecting Personal Privacy Online for tips on setting privacy controls.]]

Let's say your teen daughter went to a party at a friend's last night. Everyone was taking photos and uploading them to their Facebook pages. When your teen goes to Facebook, she discovers that her exploits are broadcast for all of her friends to see. There are even some misidentified pics of particularly wild behavior that are tagged with her name but are really of someone else.

What happened? When the photos were uploaded, Facebook's Tag Suggestions automatically compared the faces in the photos to other Facebook photos they were tagged in. And while Facebook does notify users when they're tagged -- after the fact -- you still have to go in and un-tag yourself if you don't want to be identified.

[[See Photos Gone Wild for 5 tips on combatting unwanted photos.]]

Privacy Concerns

By allowing automatic tagging, Tag Suggestions erodes the measure of control that users had by looking at each photo and determining who to tag. What if you know -- but Facebook doesn't -- that one friend asked you never to tag them. Facial recognition and automatic tagging makes it a lot easier for you to forget that promise. And while there are a few privacy measures -- you can only be tagged by friends, you're notified when you're tagged, and suggestions are based only on photos you've been previously tagged in -- the setting is on by default. If you don't want your name cropping up all over your friends' pages, you have to turn the feature off.

Lots of things benefit from automatation -- dishwashing, for example. But on the Internet, where broadcasting people's images without their consent can have very public consequences, it seems fair that auto-tagging should be an opt-in feature.

Your teen can disable Tag Suggestions using the instructions below. You can also go a step further and bar Facebook from using your image to compare photos altogether by sending a note to the company.