Freezing your credit is the single most important thing you can do to minimize your risk of identity theft. Fortunately, it's free and easy to do, although each of the Big Three U.S. credit-reporting agencies has slightly different procedures for setting it up.
Once you set up a credit freeze, only those companies with which you already do business will get to see your credit file, and it will be almost impossible for someone else to set up a new account in your name. Credit freezes are permanent until you decide otherwise.
The downside is that it'll be nearly impossible for you to set up a new account or get a new line of credit too. This will be a problem if you're trying to get a car loan or a mortgage, or even trying to switch wireless carriers.
So each credit bureau also makes it easy to "unfreeze" or "lift" the freeze temporarily or permanently. You can do so with a password or PIN, and set the effective dates and duration of the freeze-lift if it's temporary. Changes in freeze status take a couple of hours to go into effect — legally, up to 24 hours — so plan accordingly.
Freezing your credit takes only a few minutes, and you can do it online, over the phone or by mail. You'll need to have your Social Security number handy, and be prepared to answer some questions about past residences and credit accounts.
To be thorough, you'll want to freeze your credit with all three of the major credit-reporting agencies: Equifax, Experian and TransUnion. Here are links to our guides on how to set up credit freezes with each of them.