In celestial navigation for the Northern Hemisphere, what is the relationship between Polaris's altitude and the observer's latitude?

The altitude of Polaris above the horizon equals the observer’s latitude

The alignment of Polaris nearly perfectly with the Earth's rotational axis grants it unparalleled utility in navigation because its angular height directly corresponds to the observer's geographical position in the Northern Hemisphere. If an observer travels directly to the North Pole, Polaris will be directly overhead, at the zenith (90 degrees altitude). Conversely, as one travels south toward the equator, Polaris appears lower and lower in the northern sky. Upon reaching the equator, Polaris sits precisely on the horizon (0 degrees altitude). Therefore, measuring the star's angle above the horizon provides a precise measurement of the observer's latitude, which was fundamental before modern electronic methods.