An attribute is simply a piece of data about – or belonging to – an individual, such as age, hair colour, legal identity, height, qualifications, vouchers, money, a visa for travel etc.

Attributes can be more or less closely tied to a particular identity. For example, a travel visa is generally tied to an identity, as shown in a passport. But a voucher can be anonymous, ‘belonging’  to whoever happens to have possession of it. And money, pure and simple, is always anonymous.

Attributes can be issued directly by a service provider qualified to do so. Examples include: a  qualification issued by a learning provider; a credit score by a credit bureau;  a ticket by an airline, and a legal identity by a government. Such attributes can usefully be called ‘authoritative’.

Attributes can also be checked by some other trustworthy party, other than the issuer. In this case, they can usefully be termed ‘verified’ attributes. Americans often use the word ‘claim’ instead of attribute. The word ‘credential’ can also be used.