The Fast Identity Online (FIDO) Alliance is an industry group to develop authentication standards as an alternative to passwords. Apple recently joined the group (via MacGeneration).
FIDO Alliance Authentication
Other tech companies in the group include Amazon, Facebook, Google, and Microsoft. The members are working to develop a new authentication standard called Universal 2nd Factor (U2F). This is an open standard to improve regular two-factor authentication with NFC devices and USB devices, like YubiKeys.
These security devices are more secure than SMS authentication or apps that generate one-time authentication passcodes. Those tools are two-step verification. But with true two-factor authentication, the second factor is a separate device.
Browsers that support U2F include Chrome, Edge, Firefox, and Opera. Apple added support for FIDO2 security keys with Safari 13 and WebAuthn.