You've heard of identity theft by now, I'm sure. (If not, permit Dayana Yochim to fill you in via her "Avoiding Identity Theft" and "Borrower, Beware" articles.) You probably imagine that it happens when some dastardly sorts find your personal info -- such as your credit card numbers -- perhaps by rifling through your garbage. Well, yes, that's sometimes how it works. But often, the victim personally hands over such information to the fraudmeisters. It has happened to many people, even some at Fool Intergalactic Headquarters.

The practice I'm talking about is called "phishing," and here's how it works: You receive an email that seemingly comes from your bank, or your credit card company, or eBay (NASDAQ:EBAY), or (NASDAQ:AMZN), or eBay's PayPal unit, or Time Warner's (NYSE:TWX) America Online service -- some legitimate organization that may have a legitimate need for your credit card information. But alas, the email isn't actually from any of these organizations. It's just finely crafted to look like it's from them.

The email says you need to update some critical information on your account, and when you click a link, you're taken to a Web page that, again, looks convincingly official. You "update" your information, but you're actually handing it over to some con artists. Once they have it, they're off and running, charging away on your account and starting a big headache for you.

So what can you do about this emerging danger? One good response is simply to not obey the instructions when you get such an email. Ignore it, or report it. But if you can't help worrying that it might be real, look into the matter. If the email is allegedly from AOL, contact AOL on your own and inquire whether your account is up to date. If your PayPal account supposedly needs new information, go to the address you know -- -- not the address or link in the email.

Most reputable online businesses won't conduct important business like this with you via email because of problems such as phishing. They'll reach you some other way.

Here's a good bottom line, courtesy of our techies at Fool HQ: "If you don't need to give your personal information to a web site, company, or individual, don't do it! This is the safest way to prevent evildoers from stealing your identity. And of course, keep your passwords private. Avoid writing them down, and don't give them to anyone, not even technical support departments."

For more tips on making the most of your credit and avoiding various credit-related pitfalls, visit our Credit Center, which is chock full of eye-opening information (and a few jokes).

Longtime Fool contributor Selena Maranjian owns shares of eBay, Time Warner, and