Facebook doesn't believe in privacy
Everybody knows about Facebook. People love it—more than 400 million of them, in fact—because it's open, social, and boasts a global reach unlike any of its predecessors or competitors. It's got games, groups, chat and messaging features. It can hold thousands of your photos for free and help you reconnect with old friends, as well as make new ones. It allows you to find people with common interests and it enables business with free social media outlets. It's even mobile.
But it's also a highly controversial privacy concern that exposes you to a variety of dangers.
The vast majority of Facebook users brush off these privacy concerns, and that's a mistake. Facebook's owner, Mark Zuckberberg, is the youngest-ever self-made billionaire, and is somebody who firmly believes in a no-boundaries, completely open social scene. He simply "doesn't believe in it," according to an off-record chat Nick Bilton, lead technology blogger for the The New York Times‘ Bits Blog, had with a Facebook employee. How scary is that to hear about the man who manages the online lives of 400 million people?
How Facebook can destroy you
Employment: Want a job? Have a job you want to keep? Delete your drunk-at-a-party photos and shave off the "#%@$ my job" statuses, because it's likely that your employer (or potential employer) is going to run an internet search on you. And unless you have fortress-like privacy settings (discussed below), they're going to get a glimpse into your personal life. If you're seen as a partier, or somebody who disses their current/old jobs or managers, or generally shows low class, you could easily lose your job.
Identity theft: Have your address, phone number, or birthday ANYWHERE on Facebook? Be prepared to have credit cards made under your name by strangers and used feverishly without you realizing. ID thieves have absolute field days when people post private information publicly. And if you think only your friends will see your number or BBM pin in those groups, "Need your numbers," you're wrong. Almost all of them are open to friends of friends, entire networks, or all of Facebook—revealing your number to thousands, if not millions, of strangers.
Property crime: Going on vacation? Don't tell the world. A status detailing that your house will be empty for seven days exposes your property to all sorts of crime. Why take the risk?
How to stay safe
1. Use a strong password. Getting hacked can wreak havoc on your personal and professional lives and expose your private information to a greater volume of strangers.
2. Hide your birthday. And your phone number and address. Never give this information out unless by Facebook private messaging, and only to the specific few whom you fully trust. Don't even use Facebook Chat—it's proven to be glitchy, and at one point users could see private chats publicly (without the chatters even knowing).
3. Don't mention your kids. Never tag your children in photos, or allow others to. It's just not worth the risk.
4. Don't mention your vacations. Save the news until after you're back. You don't want strangers knowing when your house is vulnerable.
5. Don't let the young'uns try it out. Facebook has an age limit of 13 for account creation, but it doesn't make any effort in actually verifying the age. In truth, a person of any age with enough basic internet competency can make an account. Don't let your children make an account underage—and if they insist upon making one at 13 (which is considerably young even so), then you must insist on controlling their privacy settings. They won't understand how serious it is, but you will.
6. Keep photos to yourself. Don't post or let yourself be tagged in party photos or any photos that represent you unprofessionally, or reveal information about your location, place of work, etc. Share your photos will friends and family the old-fashioned way—in person—or send them an email.
7. Adjust your settings. This is the golden rule; it simply must be done. Go to Account -> Privacy settings, and restrict anything and everything you feel uncomfortable sharing with people beyond your friends (or even just yourself). You can also disable search engines from finding your profile, which is also a good step to take, as that's the easiest way for potential dangers to scope you out.