On an iOS device, there's a capacitive ring around the Touch ID sensor; on the new MacBook Pro, the entire Touch ID sensor is capacitive. When the sensor detects a finger, it triggers a high-resolution image capture. That image is converted into a mathematical representation myloweslife.com, which is then sent through the hardware channel to a secure enclave. If the representation matches what's stored in the enclave, a "yes" token is released and the Touch ID action is authenticated. If not, a "no" token is released, all you get is a digital head shake. Every time Touch ID scans a finger and recognizes it, it adds additional detail to the representation, theoretically to make it register even faster and better in the future.