The following column was originally published Oct. 7, 2003.

Identity theft -- the fraudulent use of your name and identifying data by someone else to obtain credit, merchandise or services -- is an equal-opportunity offense, affecting victims of all races, incomes and ages. Many don't even know they've been ripped off for a year or more after the fact. That's because identity thieves often shield their actions by using a different address when they open new accounts in the victim's name.

Typically, federal laws cap monetary losses to consumers, but even in routine cases, it takes victims more than two years on average to clear their names, according to the Privacy Rights Clearinghouse, a nonprofit advocacy group. Some victims say that during that time they haven't been able to get a car loan or a mortgage, or even use their cell phone.

Identity theft is a pernicious, pervasive crime, and all a practitioner really needs to victimize you are three pieces of information: your full name, Social Security number and date of birth. With just that, thieves can open credit or bank accounts under your name, or drain existing accounts. They can get by with even less, when financial institutions fail to check identifying information.

To help protect yourself from identity theft, you need first to recognize the ways thieves can get information about you. Here are just a few of the tricks ID thieves use, and how you can combat them:

Pretexting. E-mail spammers, telemarketers and even some clerks and salespeople use a false pretense to lure you into revealing personal information. We recommend against giving personal information to someone who has called or e-mailed you unsolicited. And if you must use e-mail to send your Social Security number or other personal data, make sure that you use a secure Internet connection by checking your browser window for a secure-connection icon.

Mail theft. Individuals and organized rings steal mail from unlocked mailboxes, trying to find letters containing personal information, preapproved credit offers and "live" checks. Homeowners and landlords can help prevent this by replacing regular mailboxes with locked boxes. Even mail that's discarded can come back to haunt you, as criminals will dig through trash (it's called "dumpster diving") for bills, medical statements or other papers that can be used to obtain credit or access to your accounts. Shredding these documents before tossing them can stymie the diver.

Salvaging discarded data. In a less-messy variation on dumpster diving, MIT graduate students were able to recover sensitive files from hard drives on one-third to one-half of the used computers they tested for a recent study. Hard-drive shredding software, or destroying the hard drives before discarding a personal computer, will delete this threat.

Skimming. Thieves use hand-held magnetic card readers that can be bought on the Internet or improvised to glean personal information off the magnetic strip on credit and debit cards. The culprits have included waiters, gas-station attendants and store clerks. Being watchful when your card is processed during purchases can help thwart this kind of theft, but a pre-emptive measure is for businesses to do a better job of screening employees.

If you do become a victim of identity theft, file a report with your local police and keep a copy for yourself. That will make it easier to prove your case to creditors and merchants, and may help you build a lawsuit if you have to sue to recover losses or clear your name later. Also, download a copy of an ID theft affidavit from the Web site of the Federal Trade Commission (www.consumer.gov/idtheft). This will help you notify merchants, financial institutions and credit bureaus.