What is a ground loop?

Mike wrote:
I've read the term ground loop in a lot of articles and accident reports but
what exactly is a ground loop?

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.