Personal data

Definition in the Law art. 4

any information relating to an identified or identifiable natural person (hereinafter ‘data subject’). An identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data or an online identifier, or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person;

In plain words

Any information about an identified or identifiable natural person is personal data. A customer’s name and telephone number fall within it, as does an online identifier linked to a particular person.