Pressure points refer to weak places in human anatomy where a person is vulnerable and where great damage can be accomplished with little effort. To knock out someone quickly, you must locate a place where you can disrupt blood pressure, oxygen or brain function. Martial artists and combat athletes can make use of these pressure points, but proper training and instruction should always be followed when learning how to take advantage of these anatomical weaknesses.
Disrupt your opponent's oxygen. Grab the front of the throat, with the webbing of your thumb and index finger against the windpipe at the base of the throat. Push the windpipe to your fingers with the thumb, making it hard for your opponent to breathe and to get enough oxygen.
Disrupt your opponent's blood flow. If blood pressure fluctuates then the body may pass out as a reboot, trying to fix itself. Put your opponent in a choke hold. From behind, reach around with your left arm, putting the windpipe snugly in the crook of your arm. Place your left hand on the inside crook of your right elbow and push the head down with your right hand. This will make the carotid arteries on the side of the neck close as they're squeezed by your arms.This hold is called the Marine Chokehold or the Japanese Strangler. Never use this hold for more than 10 seconds, as it can cause serious injury.
Disrupt your opponent's brain function. When the brain gets too much sensory input or is jarred it shuts down, resulting in unconsciousness. The temples are sensitive areas that can cause a lot of pain, and a solid blow to the jaw will cause the head to whip around, jarring the brain and causing a concussion. This will result in wooziness and likely unconsciousness.
There are many types of pressure points and weak spots that you can target. Not all of them cause unconsciousness, but they are good to know for martial artists and self defence enthusiasts alike.
Always practice in a safe environment at partial speed and strength. Pressure points are good to learn, but they are serious flaws in the anatomy that can cause intense pain or death. You want to practice learning the places and following through with techniques, but you don't want to harm your opponent, or alternatively be harmed by your opponent.