Usernames and passwords have been used for authentication since the dawn of computing. Apple has introduced many ways to facilitate the usage of strong passwords for authentication by including biometric authentication like Face ID and Touch ID with its products. Now, Apple is working on expanding Apple Watch authentication beyond simply unlocking your Mac with macOS 10.15.
Currently, there are some Macs with Touch ID, specifically the MacBook Pro models with Touch Bar and the latest MacBook Air.
The biometric mechanism can be used to unlock the Mac, authorize Apple Pay purchases, autofill usernames and passwords, and (for the more advanced users) authenticate with sudo in Terminal.
Another mechanism used for authentication on the Mac is the Apple Watch.
Users of modern Macs have the ability to unlock their machines just by wearing the Apple Watch which itself is secured by a passcode and aware of when it’s being worn. Mac users without Touch ID can also authenticate Apple Pay on the Apple Watch with a double-click of the side button where available
Read more at 9to5Mac.com