Verifying who you are.

Flow

Client
  ↓ (credentials)
Authentication System
  ↓ (verification)
Identity Verified
  ↓
Access Granted

Identity

Represents a user or system.

• Human (user)
• Machine (service, API, job)

Claims

Statements about identity.

• user_id
• email
• role
• issuer

Principal

The authenticated entity in the system.

(In Spring Security → Principal / Authentication)