Keep Your Data Safe Online: Complete Guide to Online Privacy (2 web pages).
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.
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-- Tom