I use Facebook, but I wouldn't post my credit card number there--or anything really embarrassing. You have to be careful about what information you give it and with whom you allow it to share that information.

If you've switched to Facebook's new Timeline user interface (and you may soon have no choice), you can control who can access your information through that. Otherwise, you must go to your profile. Assuming you're logged into Facebook, you can get to your profile via the URL www.facebook.com/editprofile.php.

To the right of almost every item on your profile, as well as every comment you post on your wall,

But be warned: If you comment on a friend's blog, you lose the ability to control who will see that comment. That's up to the friend who originally posted it.

You might also want to go over additional privacy settings. Click the down arrow next to the word Home in the upper-right corner of the browser window and select Privacy Settings and examine what you find.

I'm just hitting the basics here. Facebook privacy can be frighteningly scary. You might want to check out the service's privacy information page. And for issues involving the new Timeline interface, see Prep for Facebook's Timeline Layout: 6 Must-Do Privacy Tweaks.

And if you're worried about who else Facebook might be sharing your information with--you're not being paranoid; you're being reasonable. See It's time to regulate Facebook.

Read the original forum discussion.

Contributing Editor Lincoln Spector writes about technology and cinema. Email your tech questions to him at answer@pcworld.com, or post them to a community of helpful folks on the PCW Answer Line forum. Follow Lincoln on Twitter, or subscribe to the Answer Line newsletter, e-mailed weekly.