There are currently 3 budgies in this directory beginning with the letter B.
Backup codes are a possible authentication method. Basically, this is a list of codes, as known from a TAN list, which can be used one after the other to confirm identity.
Unique characteristics of a person such as the face, fingerprint, iris or voice can be used for authentication. Already today the identification of persons is possible via Touch ID, Android Fingerprint but also via other devices like webcams.