# Advanced Behaviours

- [Debugging](/v4.5/pure-php/advanced-behaviours/debugging.md)
- [User Verification](/v4.5/pure-php/advanced-behaviours/user-verification.md)
- [Authenticator Selection Criteria](/v4.5/pure-php/advanced-behaviours/authenticator-selection-criteria.md)
- [Attestation and Metadata Statement](/v4.5/pure-php/advanced-behaviours/attestation-and-metadata-statement.md)
- [Authentication without username](/v4.5/pure-php/advanced-behaviours/authentication-without-username.md)
- [Extensions](/v4.5/pure-php/advanced-behaviours/extensions.md)
- [Authenticator Counter](/v4.5/pure-php/advanced-behaviours/authenticator-counter.md)
- [Dealing with “localhost”](/v4.5/pure-php/advanced-behaviours/dealing-with-localhost.md)