Over the Christmas holiday, the Internet lit up with headlines saying Randi Zuckerberg, (yes, that Zuckerberg — Mark's sister) didn't understand Facebook privacy settings. She had posted a family photo to her friends on Facebook and it wound up on Twitter. Zuckerberg understood how Facebook privacy worksd, but a friend's betrayal left her annoyed.
"Not sure where you got this photo," tweeted Randi Zuckerberg to @cschweitz. "I posted it to friends only on Facebook. You reposting it to Twitter is way uncool."
Facebook offers privacy settings for every post you make, and they're not complicated. The network has even rolled out a backup setting feature that lets users adjust their privacy settings from their home pages, along with an inline setting and the options available in their settings menu.
The big question for most users is, "Who can see my posts?" Facebook offers several choices, including "Public" (which replaces Everyone, a previous term Facebook used to indicate that anyone could see a post), "Friends" (your entire friend list), "Friends, but not Acquaintances" (excluding the people you rarely interact with), and only you. You can designate individual friends by choosing the custom option, which will not include a sharing option when it's posted to your friend's walls. Note that Facebook has eliminated "Friends of friends."
While using the custom option is the most secure way to share content on Facebook, it doesn't guarantee your privacy. Don't blame Facebook, blame your friends. Once your post appears on a friend's feed, anything goes. A so-called friend could take a screenshot and email it to anyone or post it just about anywhere, including to Twitter.
You probably don't have a famous brother whose mundane photo would be snapped up and broadcast to the public. Still, it's important to keep in mind that nothing is really private once you post it to Facebook.
For a simple privacy tutorial, log into your Facebook account, click the new lock icon in the upper right corner and go through Facebook's Privacy Shortcuts, which taken together provide a privacy mini-tour.