# Terminology and Concepts

**Self-Sovereign Identity (SSI)** A user-centric approach to digital identity, allowing individuals and organizations to control their identifiers and credentials without centralized authorities.

**Decentralized Identifier (DID)** A globally unique identifier resolvable via the EMPE Blockchain. A DID Document includes public keys and endpoints for trust and verification.

**Verifiable Credentials (VCs)** Cryptographically signed credentials that attest to certain attributes of an entity. VCs follow W3C standards, ensuring integrity and authenticity.

**Credential Schema** A JSON-based template defining the structure, properties, and required fields of a credential type. Ensures consistency and interoperability.

**EMPE Blockchain** The ledger where DIDs are anchored, providing a trust layer that wallets and verifiers rely on for DID resolution and verification.

**One-Click Deployment Portal** A provisioning tool that automates deployment, DID registration, and initial configuration of the Issuer Service.

**Targeted Offering vs. Open Offering**

* **Targeted Offering**: Restricted to a specific recipient DID; requires DID ownership proof.
* **Open Offering**: Accessible to any wallet scanning the offering’s QR code or link; no DID proof required.

**Authorization Code Flow (Wallet Flow)** A process where the wallet authenticates and proves DID ownership, exchanging authorization codes for access tokens and, ultimately, retrieving the credential.

**Revocation List** An on-chain, privacy-preserving data structure used to indicate whether a Verifiable Credential has been revoked. Implemented as a compressed bitstring published to the EMPE Blockchain, allowing verifiers to check revocation status without revealing sensitive data. Each credential references a specific index in the list corresponding to its status.