U2F
U2F keys confirm a login after a password has been entered. FIDO2 superseded it by letting the authenticator hold the user's identity itself, which is what turned a second factor into a full replacement. See What is FIDO2?
U2F keys confirm a login after a password has been entered. FIDO2 superseded it by letting the authenticator hold the user's identity itself, which is what turned a second factor into a full replacement. See What is FIDO2?