Keep Your Data Safe Online: Complete Guide to Online Privacy

Though we can't promise that these tips will keep you 100 percent safe from hackers, they'll certainly make it a lot harder for interlopers to read your e-mail and IMs, fill your computer with spyware and track your Web-surfing habits.

Total privacy online is nearly unattainable: the Internet is about communication, and communication is inherently public. But that's not to say that you can't attain a reasonable level of privacy: when two people whisper to each other alone in a room, that communication is only public in the mind of the paranoiac.

The trick, then, is to not seek an imaginary and nebulous ideal of complete privacy. It's to train ourselves to cover our lips and whisper online: to communicate only with people and Web sites we trust, while making it as difficult as possible for people we aren't addressing to listen in. We need to secure our computers, control our outbound traffic, encrypt our information and anonymize our identity. It takes diligence to evade the prying bots, data-mining snoops and other busybodies of the digital world, but it is possible to carve out a reasonable amount of personal space on the world's most public medium.

Lock Down Your Box

In practical terms, the biggest threats to your privacy online aren't external. You're less at risk from a rogue hacker attempting to tunnel into your PC from a bunker in Serbia than you are from the programs that you've already installed on your PC and the sloppy Internet surfing habits you may have picked up over the years.

Many computers are filled with spyware—surreptitious programs that monitor your computing habits and sniff out your personal information, then pass data about you on to third parties without your knowledge. Windows users bear the brunt of this spying, and therefore should be the most diligent about protecting their PCs. The first line of defense against spyware is a firewall, a program that can prevent unapproved programs from accessing the Internet and phoning home with your information. Windows users have many options, but a basic firewall is built into both XP and Vista. Check in your Control Panel under Security settings. Your firewall should be on by default, if it is not, turn it on. Windows users looking for more sophisticated third-party solutions should consider Check Point's Zone Alarm Pro, which allows more precise control. Also built into Windows Vista and XP is Microsoft's own spyware scanner, Windows Defender, which can check to see if your machine has already been infiltrated by malware and can remove those offending programs. Again, third-party options abound—our favorites are Lavasoft's AdAware and Spybot Search and Destroy from Safer-Networking.org.

Because of its relatively low market share, the Mac OS is a less juicy plum for the earnest snoop, but no operating system is truly immune. Like Vista, OS X has a built-in firewall to keep outside entities from communicating with your computer (open System Preferences and check under Security for settings). But to protect against programs on your Mac sending info out, try installing LittleSnitch, which alerts you to any outbound traffic and highlights the offending program. And to search your Mac for potential spyware intrusions, try the free Trend Micro HouseCall online scanner.

Ultimately, the biggest security threats to your online privacy are your own bad habits. As computers become more connected and more information is stored online, it becomes even more critical that we follow good password practices. That means no pet names, no names of children or favorite sports teams either—and certainly don't make your password "password" it's the first thing hackers check. To learn to make stronger passwords, try a few of your favorites at Password Meter, a Web utility that tests the strength of your passwords as you type them in and rates their security. Remembering passwords is a chore, but the extra effort required is an indication of their inherent strength. Carrying around passwords in your head is like a keychain to your virtual private property.

Passwords, firewalls and spyware checkers will form a bulwark around your computer, but just as fences, locks and security systems won't keep out a determined burglar, these digital strategies can also fail. If you require bulletproof protection, the best defense is to encrypt your drive. Encryption algorithms are the same sort of stuff that protects top-secret government documents and corporate trade secrets. The open-source [http://www.truecrypt.org/] TrueCrypt encryption software is free for download and can encrypt files on the fly as you drag and drop them onto the drive. You should also make sure to encrypt your Wi-Fi router. Choose WPA encryption if your router has the option. This is far more secure than the older WEP option. This will reasonably guarantee that the only person accessing your network is you.