STP - a ground loop most usually happens on a tail wheel aeroplane because the center of gravity is behind the two front wheels.
While things are going normally everything is fine, but if the line of travel of the aeroplane starts to swing to one side then momentum makes the C of G keep going in the direction i.e.: out to the side!
This is why, when flying a tail wheel, you have to concentrate on keeping it under control. I was taught to use the rudder pedals as if they were the pedals on a paddle boat and that seems to work!
You can ground loop a tail wheel, even at low speed taking off or landing, if you don't keep on it. At least embarrassing... maybe dangerous. Obviously the heavier the aeroplane the harder it is to keep the C of G under control.