Hand tracking is technology for tracking hands in 3D.
It is typically done using infrared sensors and computer vision.
Hand tracking using infrared is usually slower and less accurate than electromagnetic tracking of a pen or something. IR hand tracking has trouble with visibility.
Leap motion is a company that makes hand tracking gadgets and software.
The Meta Quest Pro has a form of hand tracking, but it does not capture the full range of human motion. It also has latency and limited range for detecting the hands.