Identity theft and identity fraud are terms used to refer to all types of crime in which someone wrongfully obtains and uses another person's personal data in some way that involves fraud or deception, typically for financial gain. 

 Unlike a person’s fingerprints, which are unique to that person and cannot be used by someone else, however, another person ­can use your personal data, especially your Social Security number, bank account, credit card number, telephone calling card number, and other valuable identifying data.  If that information were to fall into the wrong hands that person could profit from it at your expense.

With more frequency, people are reporting that unauthorized persons have taken funds out of their bank or financial accounts, or, in the worst cases, taken over their identities altogether, running up vast debts and committing crimes while using the victim's names.  In many cases, a victim's losses may include not only out-of-pocket financial losses, but also substantial additional financial costs associated with trying to restore their reputation in the community and correcting erroneous information for which the criminal is responsible.

In one notorious case of identity theft, the criminal, a convicted felon, not only incurred more than $100,000 of credit card debt, he also obtained a federal home loan, and bought homes, motorcycles, and handguns in the victim's name, and then called his victim to taunt him, saying that he could continue to pose as the victim for as long as he wanted because identity theft was not a federal crime at that time.   To top it all off the criminal then filed for bankruptcy in the victim’s name.  The victim and his wife spent more than four years and more than $15,000 of their own money to restore their credit and reputation, the criminal served a brief sentence for making a false statement to procure a firearm, but made no restitution to his victim for any of the harm he had caused. This case, and others like it, prompted Congress in 1998 to create a new federal offense of identity theft.