World has launched World ID v4, introducing significant upgrades to its protocol, including account abstraction and multi-key support. This update transforms World ID into an abstract record within the "WorldIDRegistry," allowing users to authenticate across various devices with multiple authorized keys. Key enhancements include multi-key and multi-validator management, improved protocol resilience with key rotation and revocation, and a web-based reference validator for easier browser use. Additionally, the update strengthens privacy with OPRF nodes and introduces a relying party registry to prevent phishing and support future protocol fees.