Master Nakayama, the chief assistant of Master Gichin Funakoshi (founder of Shotokan style karate and father of modern karate), defined karate-do in the introduction to his book series "Best Karate", in agreement with Master Funakoshi's saying: "The purpose of karate training is not victory, but the perfection of character of the trainees."
In other words, karate-do is a martial art designed to develop the character of the trainee through training, so that the trainee will learn to face any obstacle, both physical and spiritual. Karate techniques are controlled entirely by the will power of the trainee and are aimed at the target with precision and spontaneity. The training hones various body parts into weapons, designed to work freely and efficiently. The necessary characteristic for completing this challenge is self-control. To conquer this hurdle one must first conquer one's self.
There are those who treat karate primarily as a self-defense, a means of exercise or a sport, and acknowledge (or don't) the positive changes that occur in the trainee, such as improved coordination, self-control and self-confidence, but do not view these as the goal of the training.