Spanking refers to a form of corporal punishment that involves striking the buttocks with an open hand.
Spanking is a form of discipline that involves the slapping or smacking the buttocks as punishment, or can sometimes be given with a hairbrush or paddle applied to the posterior. The giving and receivng of spankings are common in sadomasochism and BDSM relationships and sessions. Sometimes light spankings are given as foreplay in non-BDSM relationships.
There are many different ways and positions to give a spanking. One of the most common is called an OTK, or Over The Knee, spanking. This is accomplished by the spanker sitting down and putting the person to be spanked face-down across their lap. Clothes or underwear can be left on or removed as desired to expose the buttocks which are then struck with an open hand, hairbrush or paddle. A person who is to be spanked can stand up or be tied over a piece of equipment made to curve them forward called a spanking horse. In fact, spanking can occur in any position that leaves the bottom accessible to another person's hand. Spanking can be done lightly so they only impart a small stinging sensation but a hard spanking can leave welts and redden the buttocks so sitting down can be very painful for the person who was so spanked. Giving hard and painful spankings are very common in S&M and BDSM.