Simply, focus, or kime (key-may) is the concept/act of concentrating all the power that the karate practitioner is generating into as small an area as possible. (This version of focus should not be confused with the idea of focusing on what you are doing, or focusing on your opponent. It is vital that you know what you and your opponent are doing at all times).

A Shotokan practitioner should be able to generate quite a lot of power. That is only part of the story. He must also know how to pass that power on to/through his opponent. This is done through focus.

To explain focus, I will use the Forward punch as an example. As the punch is being executed, the hips torque which throws the punching arm off the body. As the arm travels out, it begins to rotate. Immediately prior to contact with the opponent, the arm completes rotation. Contact with the opponent is made with the first two knuckles of the fist. The fist is IMMEDIATELY retracted after contact. It is this making contact and retracting of the fist that is focus. The karateka is taking all her generated power and, in essence, placing (focusing) it into her first two knuckles. Upon contact with her opponent, all of that energy is transferred to her opponent. When she retracts the fist, the energy is left with the opponent.

By placing all of this energy into the smallest transfer point as possible, the karateka can have a damaging effect. Think of it this way. Take a one pound hammer (with a striking surface of 1" round) and a one pound paddle (with a striking surface of 4" round). Using each item in turn, and with the same amount of force, hit something. More damage will be caused by the hammer than the paddle. This is because the generated energy was concentrated (focused) into a smaller hitting area.

So, this leads in turn to understanding that when sparring or fighting, you want to strike with as small a hitting surface as possible. So:

1. When punching, you want to strike with the first two knuckles of the fist, not all four.
2. When kicking, hit with the ball, heel or blade of the foot, not the foot bottom.
3. When using an elbow strike, hit with the area just ahead of or just behind the point (this depends upon which type of elbow strike you are using). Yes, the elbow point is smaller area than the two I just mentioned, but you don't want to risk breaking your elbow!
4. When using a knee strike, employ the same idea as an elbow strike. Don't hit with the knee itself, but use the region just above the knee.

By striking with the smallest area, you will focus your energy and deliver more powerful blows.

By the way, I only spoke about striking techniques above, but the same principles hold for blocking and kicking techniques. Generate as much power as possible. Deliver that power to your opponent and then QUICKLY retract.