Chakra is essential to even the most basic technique in the Naruto series; it is the molding of the physical energy present in every cell of the body and the spiritual energy gained from the mind. Once molded, it can be channeled through the chakra pathway system, which is to chakra as the circulatory system is to blood, to any of the 361 tenketsu in the body. Through various methods, the most common of which is hand seals, the chakra can then be controlled and manipulated to create an effect that would not be possible otherwise, such as walking on water, exhaling fire or creating illusions.
Through the process of nature transformation, chakra can be converted into a number of different natures. Most ninja have a natural affinity to one chakra nature, but they have the capacity to use natures apart from their own affinity. There are five basic natures, but in addition to these, certain genetic traits allow multiple natures to be combined into new natures; for example, it is possible to mix Water and Wind Style into Ice. While many ninja can use more than one chakra nature, very few are able to combine them in this manner.
Because chakra takes time and a great deal of training to gradually build up, the key to its use is not actually having chakra but instead being able to sufficiently control and conserve it. This is called Chakra Control. In order to have good chakra control, a ninja should only mould as much chakra as they need to perform a given ability. If they mould more chakra than is needed, the excess chakra is wasted and they will tire out faster from its loss. If they don't mould enough chakra, a technique will not be performed effectively, if at all, likely creating problems in a combat situation.
General training methods for improving one's moulding and manipulation of chakra are the Leaf Concentration, Tree Climbing, and Water Surface Walking exercises. A good way to build up chakra in the body is to spin it into a tight spiral; Whether to spin the chakra left or right is dependent on the way the user's hair grows. Hand Seals are often used to manipulate chakra more easily, allowing shinobi to execute their techniques faster and more effectively. Shinobi who are extremely skilled at chakra control often specialise in genjutsu or become medical-nin.
- Shape transformation deals with controlling the form, movement, and potency of chakra.
- Nature transformation deals with changing the physical properties of chakra into an element. There is also the nature transformation of Yin and Yang, which deals with changing the ratio of spiritual and physical energies within chakra.
These two methods can be implemented separately or together in order to create a technique, though ninja who can use both simultaneously are said to be rare.