Personally Identifiable Information (PII) is information that identifies a single person or can be used with other information sources to identify a single person. When it is stolen, PII can be used for various nefarious purposes, including identity theft and fraud.
The U.S. government has defined PII as “Information which can be used to distinguish or trace an individual's identity, such as their name, social security number, biometric records, etc. alone, or when combined with other personal or identifying information which is linked or linkable to a specific individual, such as date and place of birth, mother’s maiden name, etc.”
The European Union has defined a similar term, "personal data,” as “any information relating to an identified or identifiable natural person ('data subject'); an identifiable person is one who can be identified, directly or indirectly, in particular by reference to an identification number or to one or more factors specific to his physical, physiological, mental, economic, cultural or social identity.”
Personally Identifiable Information is subject to a variety of forms of legally-mandated protection.