Many martial arts styles use kata and/or patterns in order to help students practice certain moves (i.e. kicking techniques, self-defense techniques and various strikes) as well as for improving a student's physical conditioning, muscle memory, focus/concentration, balance, etc. To master many of these kata, martial arts students should try to imagine that they are fighting an imaginary opponent. This allows students to practice "offensive" or "defensive" techniques (i.e. strike the imaginary opponent's neck at the correct height and angle) versus just going through the motions in order to pass a belt test. In addition, many martial arts pull out portions of a kata in order to illustrate the self-defense techniques and situations that have been incorporated in that particular kata or form. This often involves two students where one is the attacker and one is the defender. In Karate and other Japanese martial arts, this kata-related technique is known as Bunkai.