In Kanji, ki is energy; ai is joining, so kiai essentially means the joining and connection of energy. Karate kiai focus on breathing and exhaling, usually forcing a breathe out of the body using stomach muscles and intra-abdominal compartments.
We often hear kiai-s in movies, such as a battle cry before a major fight scene. 
Tennis players’ kiai-s come in the form of grunts when they are serving or taking shots. Thai boxers also kiai-s when taking punches, and they usually sound like ‘aish’. Kiai is a method of breathing to improve a game plan or to generate power into the otherwise spent fighter.
A kiai does not have to sound the same as everyone else’s. The main thing is to focus on the breath. Your kiai should originate from your belly/stomach, not your throat.
Every karatekan and karate master must be able to display the sanchin kata, which is the base technique of kiai. Techniques of kiai have been perfected through karate to create tremendous internal and external power. This is why our karate classes emphasize practice of kiai starting from white belters. Osu!
<Part 2 of this article to come>
