Nen

Nen could be described as the "fighting energy" of Hunter X Hunter. It is used by nearly all major characters and is the source of their superhuman abilities. Nen is considered to be the life and spirtual energy of a living creature so everyone including animals possesses it. The powers that is bestows are based on personality and the nen itself seem to respond to the emotions and goals of the user.

However, it normally just leaks away from nodes spreads across the body. A nen user learns to control this energy at will. Either they discover it on their own or through the help of an experience user. Normally meditation is required to sense the existence of these nodes and to learn to open and close them at will. However, a person can potentially learn how to control their nen after receiving a powerful nen attack from which they survive. The third way is similar to the second but more gentle. A skilled practicioner can project nen through a person's body and forcefully open the nodes. However, there is a distinct danger of causing injury if the person lacks skill or harbors malice. Gon and Killua began their nen training under Wing using this method, due to the time constraints of the Celestial Tower.

Nen has various basic and advanced techniques. The basic techniques, in order of study, are: Ten, Zetsu, Ren, Gyou and Hatsu.

Ten

Ten is the most basic and elementary technique of nen. It involves learning to contain the nen energy to prevent it from leaking away from the body so that it envelops the user like a bubble. This is provides basic protection against all attacks and trauma including those caused by nen itself. It even slows aging because it helps prevent the breakdown of the body. This explains the extremely advanced ages of Netero and Maha Zoldyck as well as the youthful vigor of many characters. When this technique is mastered, it becomes second-nature and a user even uses ten in their sleep.