HAP KI Do has a full range fighting arsenal to choose from, but many people know it for its ability to control and subdue an attacker through the use of joint locks, manipulation, and pressure points. There is said to be over 10,000 techniques associated with this art.

Understanding the nature of HAP KI DO requires knowledge of actual combat or self defense situations.
First, in real situations there are no rules.
Second, there is no way to predict the situations an attacker will create.
Third, an effective defense requires that your response to aggression must be by reflex and appropriate for the particular attack.
HAP KI DO has techniques to deal with and respond appropriately to any type of attack.

Since you cannot predict how someone will attack (strike, kick, grap, weapon, etc), you must be ready to handle anything. When a HAP KI DO practitioner is attacked, his training is to react reflexively (thinking is too slow) to the attacker rather than with predefined forms.

PHILOSOPHY
The philosophy of Hap Ki Do is based on three guiding principles: Yu, Won, and Hwa

YU: FLOWING WATER
The Hap Ki Do practitioner does not meet force with force but rather adapts to the flow of the attack in order to redirect it to the practitioner's advantage, much like water can adapt to multitude of surroundings. Hap Ki Do trains one to adapt to one's situation.

WON: CIRCLE
The techniques of Hap Ki Do are performed by utilizing the circular motion to minimize the effect of an attack while simultaneously positioning the practitioner to counterattack. Circular movement facilitates the flow of ki or energy thus efficiently directing energy and never wasting it.

HWA: HARMONY
To harmonize one's mind, body, and techniques through continuous practice and be able to blend that harmony through the opponents attack, one is able to achieve a devastating affect. Harmony is based on combining energy. In other words, Hap Ki Do techniques are based on blending or harmonizing with one's opponent versus meeting force against force.