Personally Identifiable Information (PII)

Personally identifiable information is any data that identifies a specific person, either on its own or combined with other data the holder already has.

Direct identifiers such as a name, national ID number, phone number or email address point to one person on their own. Indirect identifiers such as an IP address, a device ID, a precise location or a birth date combined with a postcode reach the same result together. The term PII is American in origin and narrower in scope; European law uses personal data, which explicitly covers online identifiers including cookie IDs and IP addresses, so data outside PII under one framework can be personal data under another. A frequent misreading is that hashing an email removes it from scope: a hash is a stable pseudonym, and while re-linking to the person remains possible it still counts as personal data.