A Hall effect sensor is basically a tiny magnet detector. When a magnet comes near it, the sensor can “feel” the magnetic field and tell the circuit, usually by turning its output on or off. We can use it to detect things moving, like wheels spinning or doors opening.
Some microcontroller pins can act like tiny batteries (power) or tiny paths to ground. By setting a pin HIGH, it gives a little voltage to power something. By setting it LOW, it acts like ground, letting current flow back. This is useful for testing or powering small sensors,
In short: Hall sensors feel magnets, and digital pins can sometimes act like tiny power sources or grounds to help run them.
