Why do stars seem to wander across the night sky?

The stars do not 'Wander'. The apparent change in their positions in the night sky is due to the fact that the Earth, and we along with it, are in a constant state of rotation. As such, our rotational movement happens below that of the stars. If one looks at the night sky in the northern hemisphere, only one star does not appear to move. Therefore, it is known as the fixed star. Incidentally, it is positioned exactly above the North Pole and hence is also called the 'pole star'. It is a good aid in determining directions in the dark, being forever present in the north. Earlier, it helped sailors to find their way in the seas.