Introduction
Core Concepts
World ID is built for easy integration, but here are a few core concepts that are helpful to understand before you start.
Proof of Personhood
"Proof of Personhood" is distinct from many existing identity systems. It is a way to prove that a person is unique, without revealing any personal information. World ID is not KYC, and it does not disclose your identity or previous actions to anyone.
World ID supports multiple "Verification Levels" to prove that a person is a unique human. These levels provide different degrees of humanness assurance, accessibility, and protection against fraud.
| Verification Level | Humanness Level | Description |
|---|---|---|
 Device | Medium | Unique mobile device check. |
 Orb | Strong | Biometric verification, uniqueness through iris (details). |
 Orb+ | Very Strong | Orb verification, plus authentication which verifies the person using World ID is the legitimate holder. |
Vocabulary
Some terms are used throughout the World ID documentation. Here are a few of the most important ones:
- World ID: A user's self-custodial identity, as well as the name of the protocol.
- Zero-Knowledge Proof (ZKP): A cryptographic method to prove that a statement is true without revealing any information about the statement itself. World ID uses ZKPs to prove that a user is verified without revealing the user's identity.
- Nullifier Hash: A component of the World ID ZKP; a unique identifier for a combination of a user,
app_id, and action. It is used to prevent sybil attacks and ensure a user is only able to perform an action once. - Signal: A component of the World ID ZKP; data attached to the proof that cannot be tampered with. An example may be a user's choice for a governance proposal.