What is a ground loop?

In article , john smith
writes

A ground loop is what happens when a taildragger pilot isn't fast enough
on the rudder pedals to keep the tail from passing him/her while going
down the runway.
Because the center of gravity is behind the main landing gear on a
taildragger, the tail of the airplane wants to swing around to the
front.
The center of gravity is forward of the main gear on a tricycle gear
airplane, so the nose wants to stay out in front.

It seems to me that this explanation, though common, is oversimplified.
What we are talking about is stability. When an aircraft (or a car for
that matter) turns on the ground a sideways force is developed on the
wheels. There is also a force generated by the sideways acceleration at
the cg and, also, in the case of the aircraft, a side aerodynamic force.
If the combined reaction of the first two is behind the cg than the yaw
motion on the ground will be unstable and may or may not be able to be
controlled by the pilot with the rudder.

It is not that the main wheels are in front of the cg so much as that
the side force developed by the tail wheel is very small (even smaller
if it is a castoring tail wheel) and too much of the side ground force
will be developed by the 'main' wheels.

You only need to be fast on the rudder because the position is unstable.
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