The definitions of the terms presented below are taken from the book “Terminology of  W3C“.

The following terms are used to describe concepts in this specification.

• Claim
  An assertion made about a subject.
• Credential
  A set of one or more claims made by an issuer. A verifiable credential is a tamper-evident credential that has authorship that can be cryptographically verified. Verifiable credentials can be used to build verifiable presentations, which can also be cryptographically verified. The claims in a credential can be about different subjects.
• Data minimization
  The act of limiting the amount of shared data strictly to the minimum necessary to successfully accomplish a task or goal.
• Decentralized identifier
  A portable URL-based identifier, also known as a DID, associated with an entity. These identifiers are most often used in a verifiable credential and are associated with subjects such that a verifiable credential itself can be easily ported from one repository to another without the need to reissue the credential. An example of a DID is did:example:123456abcdef.
• Decentralized identifier document
  Also referred to as a DID document, this is a document that is accessible using a verifiable data registry and contains information related to a specific decentralized identifier, such as the associated repository and public key information.
• Derived predicate
  A verifiable, boolean assertion about the value of another attribute in a verifiable credential. These are useful in zero-knowledge-proof-style verifiable presentations because they can limit information disclosure. For example, if a verifiable credential contains an attribute for expressing a specific height in centimeters, a derived predicate might reference the height attribute in the verifiable credential demonstrating that the issuer attests to a height value meeting the minimum height requirement, without actually disclosing the specific height value. For example, the subject is taller than 150 centimeters.
• Entity
  A thing with distinct and independent existence, such as a person, organization, or device that performs one or more roles in the ecosystem.
• Graph
  A network of information composed of subjects and their relationship to other subjects or data.
• Holder
  A role an entity might perform by possessing one or more verifiable credentials and generating presentations from them. A holder is usually, but not always, a subject of the verifiable credentials they are holding. Holders store their credentials in credential repositories.
• Identity provider
  An identity provider, sometimes abbreviated as IdP, is a system for creating, maintaining, and managing identity information for holders, while providing authentication services to relying party applications within a federation or distributed network. In this case the holder is always the subject. Even if the verifiable credentials are bearer credentials, it is assumed the verifiable credentials remain with the subject, and if they are not, they were stolen by an attacker. This specification does not use this term unless comparing or mapping the concepts in this document to other specifications. This specification decouples the identity provider concept into two distinct concepts: the issuer and the holder.
• Issuer
  A role an entity can perform by asserting claims about one or more subjects, creating a verifiable credential from these claims, and transmitting the verifiable credential to a holder.
• presentation
  Data derived from one or more verifiable credentials, issued by one or more issuers, that is shared with a specific verifier. A verifiable presentation is a tamper-evident presentation encoded in such a way that authorship of the data can be trusted after a process of cryptographic verification. Certain types of verifiable presentations might contain data that is synthesized from, but do not contain, the original verifiable credentials (for example, zero-knowledge proofs).
• Repository
  A program, such as a storage vault or personal verifiable credential wallet, that stores and protects access to holders’ verifiable credentials.
• Selective disclosure
  The ability of a holder to make fine-grained decisions about what information to share.
• Subject
  A thing about which claims are made.
• Validation
  The assurance that a verifiable credential or a verifiable presentation meets the needs of a verifier and other dependent stakeholders. This specification is constrained to verifying verifiable credentials and verifiable presentations regardless of their usage. Validating verifiable credentials or verifiable presentations is outside the scope of this specification.
• Verifiable data registry
  A role a system might perform by mediating the creation and verification of identifiers, keys, and other relevant data, such as verifiable credential schemas, revocation registries, issuer public keys, and so on, which might be required to use verifiable credentials. Some configurations might require correlatable identifiers for subjects. Some registries, such as ones for UUIDs and public keys, might just act as namespaces for identifiers.
• Verification
  The evaluation of whether a verifiable credential or verifiable presentation is an authentic and timely statement of the issuer or presenter, respectively. This includes checking that: the credential (or presentation) conforms to the specification; the proof method is satisfied; and, if present, the status check succeeds. Verification of a credential does not imply evaluation of the truth of claims encoded in the credential..
• Verifier
  A role an entity performs by receiving one or more verifiable credentials, optionally inside a verifiable presentation for processing. Other specifications might refer to this concept as a relying party.
• URI
  A Uniform Resource Identifier, as defined by [RFC3986].