In the fetish context, it most often refers to chastisement on the buttocks between consenting adults.
Whereas spanking tends to be used to mean blows to the buttocks with the hand, CP usually involves implements such as paddles, straps or canes ... or one of many objects that can be pressed into service to give a satisfying sting to a willing rear end!
It has been suggested that the pleasure obtained from a spanking is similar to the "Runners High" achieved after a period of strenuous exercise. The pain triggers the release of opiate-like substances called endorphins – hormones that make you feel good. The feeling of well-being can relieve stress and help with relaxation.
See spanking, paddling, caning
"Anyone around here into a bit of CP for fun?"