Internet site legal identity theft is becoming increasingly more sophisticated and common. If successful, a third party can use the theft of a legal identity to secure confidential information, harm marketing brand value, diminish good will and steal customers. Internet sites may employ legal, business, and technological means to protect their legal identities.

Most commonly, identity theft arises when one party uses another party's personal identifying information. The most common pieces of information include: full name, home address, email address, social security number, passport number, driver's license number, credit card numbers, and date of birth. Such information is deliberately used by one party to deceive another party so as to gain financial advantages or obtain credit and other benefits, and to cause other person's disadvantages or loss.

Both people and businesses are subject to identity theft. Business identifiable information, as defined in the Freedom of Information Act, includes trade secrets and commercial or financial information that is confidential (5 U.S.C. §552(b)(4)). The use of either personal or business identifying information, without permission, is usually for the purpose of commiting fraud or other crimes.