FIDO2 is an improvement over the U2F standard, mainly with the ability to now perform password-less logins [1][2]. This had to do with a shortcoming in the U2F

FIDO2 is an improvement over the U2F standard, mainly with the ability to now perform password-less logins [1][2]. This had to do with a shortcoming in the U2F protocol and/or devices such that they didn't need to have much storage on these devices [3]. To address this, the new FIDO2 devices are now required to persist your username(s) for a particular site. The new CTAP2 protocol has also been extended to accommodate more sophisticated authenticators, like those crypto-currency wallets with a display. If you are looking for devices, check out reviews of various devices by agl [4] and Brad Hill [5]. [1] https://www.yubico.com/2018/04/yubico-and-microsoft-introduce-passwordless-login/ https://www.yubico.com/2018/04/yubico-and-microsoft-introduc... [2] https://fidoalliance.org/fido2/ https://fidoalliance.org/fido2/ [3] https://www.yubico.com/2014/11/yubicos-u2f-key-wrapping/ https://www.yubico.com/2014/11/yubicos-u2f-key-wrapping/ [4] https://www.imperialviolet.org/2017/10/08/securitykeytest.html https://www.imperialviolet.org/2017/10/08/securitykeytest.ht... [5] https://github.com/hillbrad/U2FReviews https://github.com/hillbrad/U2FReviews