They engage various parts of the arm with the hand and are held in different positions such as knife-hand, closed fist etc.
Each block is suitable for a particular kind of attack and may be combined with another punch or kick to make a counter-attack.
The self-defense applications would be difficult to score in sparring as they are designed primarily to cause injury or quickly incapacitate an adversary.
Many Taekwondo clubs include self-defense in their daily routine in both WTF and ITF.
For real life combat situations, an experienced Taekwondo practitioner is versed in the following: Linear Techniques These include mostly punching, kicking, headbutts and other striking maneuvers.
With proper execution opponents may be incapacitated with a single blow, which lessens the number of attacks in encounters with multiple people.
Soft self-defense techniques like the stranglehold or joint lock can be used to subdue the attacker, avoiding dealing permanent injury.