A Hall effect sensor is a device that detects and measures the strength of a magnetic field by producing a voltage proportional to the field's strength, based on the principle that when an electrical current flows through a conductor placed within a perpendicular magnetic field, a voltage difference develops across the conductor, known as the Hall effect; essentially, it converts magnetic field information into an electrical signal.
Meaning that it senses movement by the Hall effect produced in the physical movement. So not subject to degradation of hardware normally present in resistance based sensors.
