> For the complete documentation index, see [llms.txt](https://docs.hypersign.id/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hypersign.id/hypersign-id/concepts.md).

# Concepts

- [Facial Recognition](https://docs.hypersign.id/hypersign-id/concepts/facial-recognition.md)
- [ID Verification (via OCR)](https://docs.hypersign.id/hypersign-id/concepts/id-verification-via-ocr.md)
- [Reusable KYC](https://docs.hypersign.id/hypersign-id/concepts/reusable-kyc.md)
- [Encrypted Data Vault (EDV)](https://docs.hypersign.id/hypersign-id/concepts/encrypted-data-vault-edv.md)
- [Facial Authentication](https://docs.hypersign.id/hypersign-id/concepts/facial-authentication.md)
- [Issuer Marketplace](https://docs.hypersign.id/hypersign-id/concepts/issuer-marketplace.md)
- [Security](https://docs.hypersign.id/hypersign-id/concepts/security.md)
- [Privacy](https://docs.hypersign.id/hypersign-id/concepts/privacy.md)
- [Credentials Types](https://docs.hypersign.id/hypersign-id/concepts/credentials-types.md)
- [Personhood Credential](https://docs.hypersign.id/hypersign-id/concepts/credentials-types/personhood-credential.md)
- [Passport / Govt. ID Credential](https://docs.hypersign.id/hypersign-id/concepts/credentials-types/passport-govt.-id-credential.md)
- [zk Proof  Types](https://docs.hypersign.id/hypersign-id/concepts/zk-proof-types.md)
- [Proof Of Personhood (PoP)](https://docs.hypersign.id/hypersign-id/concepts/zk-proof-types/proof-of-personhood-pop.md)
- [Proof Of KYC (PoK)](https://docs.hypersign.id/hypersign-id/concepts/zk-proof-types/proof-of-kyc-pok.md)
- [Proof Of Age (PoA)](https://docs.hypersign.id/hypersign-id/concepts/zk-proof-types/proof-of-age-poa.md)
- [Uniqueness Check](https://docs.hypersign.id/hypersign-id/concepts/uniqueness-check.md)
- [Credential Revocability](https://docs.hypersign.id/hypersign-id/concepts/credential-revocability.md)
- [Machine Readable Zone (MRZ)](https://docs.hypersign.id/hypersign-id/concepts/machine-readable-zone-mrz.md)
- [Liveliness Check](https://docs.hypersign.id/hypersign-id/concepts/liveliness-check.md)
- [Zero Knowledge Proof (zkp)](https://docs.hypersign.id/hypersign-id/concepts/zero-knowledge-proof-zkp.md)
- [Introduction](https://docs.hypersign.id/hypersign-id/concepts/zero-knowledge-proof-zkp/introduction.md)
- [zk-SNARK](https://docs.hypersign.id/hypersign-id/concepts/zero-knowledge-proof-zkp/zk-snark.md)
- [Circuits](https://docs.hypersign.id/hypersign-id/concepts/zero-knowledge-proof-zkp/circuits.md)
- [SSI and ZKP](https://docs.hypersign.id/hypersign-id/concepts/zero-knowledge-proof-zkp/ssi-and-zkp.md)