The pile hitch is a kind of hitch, which is a knot

Knot

A knot is a method of fastening or securing linear material such as rope by tying or interweaving. It may consist of a length of one or several segments of rope, string, webbing, twine, strap, or even chain interwoven such that the line can bind to itself or to some other object—the "load"...

 used for attaching rope to a pole or other structure. The pile hitch is very easy to tie and can be tied in the bight, without access to either end of the rope, making it a valuable tool.

To tie, form a loop in the bight, and wrap both strands of this loop around the pole near the pole's end. Pull the loop around and under the rope, then finish by putting the loop itself around the end of the pole.