The definition of PII, used throughout the federal government including the Department of the Navy (DON) comes from the Office of Management and Budget (OMB) Circular A-130, Managing Information as a Strategic Resource is: "Personally identifiable information means information that can be used to distinguish or trace an individual’s identity, either alone or when combined with other information that is linked or linkable to a specific individual.

One critical aspect of the Privacy Act is to protect personally identifiable information (PII). What is PII? PII is information that can be used to determine an individual’s identity. One element of PII may be enough to identify an individual. In other cases, more than one element of PII can be combined to identify an individual.

The Privacy Act of 1974 as amended at 5 U.S.C. 552a, is a code of fair information practices which mandates how Federal agencies, like the Department of Defense, maintain personally identifiable information (PII), i.e., records that uniquely identify you.