Here’s the bottom line: if you use Facebook, and your friends sign up for social applications, your name and details could appear in unexpected places. Of course, you could always not have a Facebook account – that’s the catch-all answer frequently trotted out by the site’s detractors. For many people, though, that’s not an easy option. When your friends run their social lives through the service, not having a Facebook account is like not having a mobile phone or an email address. Yes, you can live without it, but it’s a serious inconvenience that means you’re very much out of the loop. So check your privacy settings, under “Apps and Websites”. You may be surprised what data your friends are giving away – and where it’s ending up.