Chakra (meaning "Chakura") is the energy source essental to even the most basic jutsu; it is a mixture of the physical energy present in every cell of the body and the spiritual energy gained from exercise and experience. Once mixed, it can be channeled through the chakra circulatory system, which is to chakra as the regular circulatory system is to blood, to any of the 361 chakra points in the body. Through various methods, the most common of which is hand signs, the chakra can then be manipulated to create an effect that would not be possible otherwise, such as walking on water, exhailing fire or creating illusions.
By mixing different ratios of the two energies, new types of chakra can be formed. The most common product is elemental chakra, which is used to perform elemental jutsu. Most ninja have a natural affinity to one type of chakra, but they have the capacity to create elemental chakra apart from their own affinity. There are six basic types, each stronger and weaker to another; five nave been shown so far, but their relations, weaknesses, and strengths to each other are all explored, the sixth dealing with Yin and Yang and the balance of mental and physical energies. In addition to these six elements, certain kekkei genkai can mix elemental chakra to form new elements, such as ice (wind and water), wood (earth and water), and lava (earth and fire). While many ninja can use more than one type of chakra, they cannot use them simultanously.
Normal chakra is a form of energy all living individuals naturally produce to some degree. Contained in the "chakra coils" that mainly surround and connect to each chakra-producing organ, the energy circulates throughtout the body in a network called "chakra circulatory system". Certain groups, such as ninja have learned to generate more chakra and release it outside their bodies through their
Normal Chakra"chakra points" in order to preform special techniques (jutsu). Chakra is not normally visible to the human eyes, though chakra can be seen in situations where a person releases as much of their chakra as possible. This is rarely seen due to the restrictions of certain chakra points (the Eight Inner Gates), limiting the amount of chakra an individual can release at a single given time. Chakra can also be visible when doing a specific jutsu (such as the Rasengan) which take a high degree of chakra control to perform.
Out of the many different type of jutsu, ninjutsu, genjutsu, dojutsu, and so on, all require the use of chakra. However, taijutsu is different, usually requiring no chakra use whatsoever. Stamina is all that is needed. While the ninja still needs a set amount of chakra to live (i.e. life force energy), regular taijutsu dosen't require any active molding or manipulation of chakra (with few exceptions). A standard attack like a punch or kick falls into this jutsu category.
Chakra is the resulting form of energy are mixed together. The two energies are referred as "physical energy" and "spiritual energy". Physical energy is collected from the body's cells and can be increased through training, stimulants, and exercise. Spiritual energy is derived from the mind's consciousness (i.e. the soul) and can be increased through studying, meditation, and experience. Having these two energies become more powerful will in-turn make the created chakra more powerful. Therefore, praticing a jutsu repeatedly will build-up experience, building up one's spiritual energy, and thus allowing more chakra to be created. As a result, the ninja is able to do that same jutsu with more power. This same cycle applies for physical energy, except this time, instead of doing things like meditation, the ninja could, say, do push-ups.
The general term for the source of chakra, the overall physical and spiritual energy an individual has, is called "total stamina". The maxium amount of chakra an individual can create and retain at a given time is called "Chakra Level".
Elemental ChakraBased on which ninjutsu the ninja uses, the amount of chakra will be different, as would the element the ninja employs. The five main elemental types are also names for the Five Great Nations: Fire, Wind, Lightning, Earth and Water. Every ninja has the potential to better utilize one of these styles and potentially more. Rinnegan users somehow have the ability to control all five elements.
Advanced elements such as Wood Style and Ice Style are created of combining different elemental chakra types. Doing this is only possible with a kekkei genkai or having a tailed beast with such an element in canon.
While that are some advanced elements that anyone can use, such as Dark Style and Steel Style of different elemental chakra types, and descentant chakra types as Speed Style, Inferno Style and Psychic Style.
However, dragon wielders have the ability to use perform an advanced chakra nature with a bloodline through training with the dragons, only a few clans or people have the power to learn the ways of a dragon or by them.
Tailed Beast ChakraThe tailed beasts are ancient malevolent demons with immense supplies of chakra. In fact, they are nothing more than concentrations of chakra that have taken on a corporeal form (mind and body). During the Great Ninja Wars, each country's Hidden Village tried to make use of the tailed beasts for military purposes and competed for them. However, no one was able to truly bring the tailed beasts under control. The only way to partially control them is to seal them within a human with powerful sealing jutsu. The host of the tailed beasts are known as the jinchuriki.
The jinchuriki can tap into their tailed beast's chakra for his or her own power; however, using such chakra can be harmful to the jinchuriki, with host's body and mind being influnced or even taken over by his or her beast. In the case, with Naruto Uzumaki, when he used the Nine-Tailed Demon Fox's chakra and reached hid four-tailed form, the chakra was so concentrated around his body that it constantly burned his flesh and repaired his body right away, shorten his lifespan. Tapping into such unnatural chakra is very harmful to the jinchuriki, as the host's personality get supressed by the animalistic blood lust of the tailed beasts and intensity of chakra will harm the jinchuriki if used for extended periods of time. As an expection, where a jinchuriki has control over his tailed beasts, these ill-effects are not evident as in the case of Killer Bee, when he creates a chakra cloak by drawing on part of his tailed beast's power or fully releasing the Eight-Tails' body, no damage can be seen from his body. With Naruto having learned to control the Nine-Tails, such damage to his body may now be avoided, but this is yet to be seen.