A Vulcan method of subduing an opponent by squeezing a nerve cluster at the base of the neck, causing instant unconsciousness without lasting harm, and Spock's signature way of ending a fight.
The Vulcan nerve pinch is applied with the fingers to the junction of neck and shoulder. Pressure on the nerves there makes most humanoids collapse at once, unharmed. It reflects the Vulcan preference for ending violence with the least possible injury.
Spock first uses it in The Enemy Within, and it recurs throughout the original series and films. The move was suggested by Leonard Nimoy, who felt that striking a man from behind was out of character for Spock.
The technique is hard for non-Vulcans to learn, and Kirk admits as much in The Omega Glory. Even so, Data uses it on a Romulan in Unification II, Jean-Luc Picard on a thief in Starship Mine, and Seven of Nine and several Vulcans of later series employ it too.