Previous sections discussed why a custom hardware device using iris biometrics is the only approach to ensure inclusivity (i.e. everyone can sign up regardless of their location or background) and fraud resistance, promoting fairness for all participants src: https://whitepaper.worldcoin.org/technical-implementation

The Orb associates the public key with a user’s iris code, whose current sole purpose is to be used in the uniqueness check. If this check succeeds, the World ID public key gets inserted into an identity set maintained by a smart contract on the Ethereum blockchain. The updated state is subsequently bridged to Optimism and Polygon PoS so World ID can be used natively on those chains.