Science of disturbing a spinning top

[kundukoustav]

In case of a spinning top, why is it that when it is deflected, it again returns to it's original spinning track?
Like suppose it is spinning. And then, we disturb it by our hand. It deflects momentarily, yet, it again returns to its own spinning axis? Can you explain the reason?

 

[haruspex]

When disturbed, the top finds itself spinning on the lean. Gravity is therefore applying a torque. But gyroscopes respond to a torque (at right angles to the axis of spin) paradoxically: they turn at right angles to both axes, i.e. they precess.
If the point of the top were constrained, e.g. by being in a depression, the top would continue to precess at the same lean. But being free to move around, the rotating tip acts like a wheel. Without going through the calculations, I would guess that this results in the tip shifting to come back under the c.o.g., thereby restoring it to the vertical.