Personally identifiable information (PII) is used in the US but no single legal document defines it. PII is often referenced by US government agencies and non-governmental organizations.
According to the National Institute of Standards and Technology:
PII is any information about an individual maintained by an agency, including (1) any information that can be used to distinguish or trace an individual‘s identity, such as name, social security number, date and place of birth, mother‘s maiden name, or biometric records; and (2) any other information that is linked or linkable to an individual, such as medical, educational, financial, and employment information.
Personally identifiable information can be divided into two categories: linked information and linkable information.
Linked information is any piece of personal information that can be used to identify an individual and includes, but is not limited to, the following:
Social security number
Driver’s license number
Credit card numbers
Date of birth
Linkable information, is information that can identify a person when combined with another piece of information could identify, trace, or locate a person.