of shoes, preferred currency. Traits are features of the subject that are inherent, such as eye colour, nationality, place of birth. Although attributes of a subject can change easily, traits change slowly, if at all. A digital identity also has entity relationships derived from the devices, environment and locations from which an individual is active on the Internet. Technical aspects Issuance Digital identities can be issued through digital certificates. These certificates contain data associated with a user and are issued with legal guarantees by recognized certification authorities. Trust, authentication and authorization In order to assign a digital representation to an entity, the attributing party must trust that the claim of an attribute (such as name, location, role as an employee, or age) is correct and associated with the person or thing presenting the attribute. Conversely, the individual claiming an attribute may only grant selective access to its information (e.g., proving identity in a bar or PayPal authentication for payment at a website). In this way, digital identity is better understood as a particular viewpoint within a mutually-agreed relationship than as an objective property. Authentication Authentication is the assurance of the identity of one entity to another. It is a key aspect of digital trust. In general, business-to-business authentication is designed for security, but user-to-business authentication is designed for simplicity. Authentication techniques include the presentation of a unique object such as a bank credit card, the provision of confidential information such as a password or the answer to a pre-arranged question, the confirmation of ownership of an email address, and more robust but costly techniques using encryption. Physical authentication techniques include iris scanning, handprinting, and voiceprinting; those techniques are called biometrics. The use of both static identifiers (e.g., username and password) and personal unique attributes (e.g., biometrics) is called multi-factor authentication and is more secure than the use of one component alone. Whilst technological progress in authentication continues to evolve, these systems do not prevent aliases from being used. The introduction of strong authentication for online payment transactions within the European Union now links a verified person to an account, where such person has been identified in accordance with statutory requirements prior to account being opened. Verifying a person opening an account online typically requires a form of device binding to the credentials being used. This verifies that the device that stands in for a person on the Internet is actually