Personally identifiable information (PII) refers to any information that could potentially identify a specific individual (or enable someone to contact that individual).
It includes ‘linked’ information such as an individual’s name, home address, email address, government-issued ID number, etc. It also includes ‘linkable’ information (place of birth, religion, gender, etc.) which, when used on its own, may not be enough to identify a specific individual, but when it is used in combination with other data could identify a specific individual.
Any data that can be used to deanonymise previously anonymous data is classed as PII. PII is a key term used in US privacy law; however, in the European Union, under the General Data Protection Regulation (GDPR), the term ‘personal data’ is used, which covers a wider range of information.