Chakra

Essential to even the most basic jutsu, chakra is mixture of the 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 (called tenketsu) in the body. Through various methods, the most common of which is Hand Seals, the chakra can then be manipulated to create an effect that would not be possible otherwise, such as walking on water.

By mixing different ratios of the two energies, new type of chakra can be formed. The most common product is elemental chakra, which is use to perform elemental jutsus. 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 elements, each stronger and weaker to another; five have been shown so far, but their relations, weaknesses, and strengths to each other are all explored with the unnamed sixth seemingly skipped. In addition to these six elements, certain Kekkai Genkai can mix elemental chakra to form new elements, such as ice (wind and water) and wood (earth and water). While many ninjas can use more than one type of chakra, they cannot use them simultaneously (with few exceptions).

Normal Chakra
Normal chakra is a form of energy all individuals naturally produce. Chakra circulates inside the human body, similar to the cardiovascular system, but can also surface outside the body. Normal chakra is not normally visible to the human eye when it is use to perform a jutsu (in the manga visible chakra is usually yellow, in the anime the chakra is blue). Chakra is visible in situations where a person is releasing as much of their chakra as possible, though this is rarely seen. Chakra is also visible to do specific jutsus (Kaiten, Rasengan, etc), which take a high degree of chakra control to perform.

Out of the many different types of jutsus: Ninjutsu, Genjutsu, Doujutsu, and so on, all require the use of chakra. However, Taijutsu is different. It basically requires no chakra use whatsoever. Stamina is all that is needed. While the ninja still needs chakra to live, regular Taijutsu doesn'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 when 2 other forms of energy are mixed together. The 2 energies are referred to as "physical energy", which is collected from the body's cells and can be increased through training, stimulants, and exercise, and "spiritual energy", which is derived from the mind's consciousness and can be increased through studying, meditation, and experience. Having these 2 other energies become more powerful will in-turn make the created chakra more powerful. Therefore, practicing 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 a person has, is "total stamina".

Chakra takes time and lots of training to gradually build up. So what's really the key is not actually having chakra, but being able to sufficiently control it. Because, everyone has chakra, but only skilled ninja can correctly "mold" and "manipulate" it to it's fullest extent.

Molding chakra means to extract energies from both the body's cells and the mind's consciousness, then mixing them together within the individual. The amount of each energy will differ from the type of technique the ninja wishes to execute. In other words, a ninja could create too much or too little chakra for a given jutsu, and the chakra cannot be used effectively. In addition, even if a ninja is able to mold the correct amount of chakra, if they aren't able to manipulate the chakra properly, the technique won't be as effective or not executed at all. Wasting energy will create a weakness of not being able to fight for a long period of time. The general term for the exact molding and manipulation of chakra is "chakra control".

As an in-between stage, some ninjas can partially control their chakra. This means they can use their chakra, but not effectively control it, which results in poorly executed justu, and more importantly, running out of chakra early in a fight. To manipulate their chakra more easily, hand seals can be used. With these hand seals, users can control their chakra with higher efficiency, allowing them to execute their jutsu more effectively. Different jutsus require a different hand seals.

Basic Elemental Chakra
Based on which jutsu the ninja uses, the type and amount of chakra will be different as would the elements you would be to employ. The five main elemental types are also the names for the Five Great Shinobi Nations: Fire, Wind, Lightning, Earth and Water. Each ninja has the potential to better utilize one of these styles and potentially more. A sixth element has been mentioned but has not been revealed. A special elemental detecting paper is used to determine ones type. When the ninja imbues the paper with a portion of their chakra, the paper will alter to reveal one's type. Fire = burn, water = wet, earth = turn to dust, lightning = crumple, wind = cut in half.

The strengths and weaknesses of elemental chakras are as follows: Fire is strong against Wind, Wind is strong against Lightning, Lightning is strong against Earth, Earth is strong against Water, and Water is strong against Fire. Chakra types such as wood and ice are the result of combining different elemental chakra types, such as the Kekkei Genkais Wood Release, of the First Hokage, Lava Release, of the Four-Tailed Jinchuriki and the Ice Release, of Haku.

Eight Gates Chakra
By opening all of the body's limit restrictions on how much chakra can be used at once, a Ninja can access 100% of their total stamina (chakra capacity), using up all the energy within each of the user's cells. These limit restrictions are known as the 8 gates. One's own muscles and chakra are so powerful that using them to their full capacity will destroy them, literally making the muscles explode or rip into pieces. Having this amount of chakra can only be used temporarily, and kills the user if all gates have been unlocked. The fewer gates unlocked, the longer the user has until the attack kills them. Because this attack is so dangerous it is classified as kinjutsu. This technique will cause some of the chakra emitting from the user to turn green, although it is still normal chakra; the color change possibly being due to the large amount being utilized when performing the technique, or because Lee's normal chakra is innately the color green.

Orochimaru's Cursed Seal Chakra
Orochimaru gives many of his subordinates a cursed seal to increase their power in exchange for their free will. To do this, Orochimaru first bites the target on the neck, leaving a seal composed of three identical marks arranged in a circular pattern. The target then loses consciousness. If the target survives, he/she would wake up with a level 1 cursed state. The curse seal works by forcibly drawing chakra from the body, allowing the user to release more chakra than they normally are capable of. The curse seal then alters the user's chakra, making it more powerful and sinister.

The seals differ from user to user. When inactive, the cursed seal is just like a small tattoo. Once active to level 1, the tattoo spreads to their whole body. On level 2, the seal covers the whole body, giving demon-like mutation to the user, including yellow demonic eyes. The curse seal slowly eats away the user's personality, making them increasingly malicious. A prolonged activation of the curse seal also depletes the user's total chakra supply (stamina) more quickly, shortening the amount of time they can fight and leaving them extremely exhausted.

Orochimaru began developing his cursed seal while he was still in Konoha and after he left (on Anko and 9 others). He later perfected it after experimentation on a prisoner named Jugo. Jugo's body naturally produces an enzyme that triggers a mutative state. The difference between Orochimaru's seals and the unrefined enzyme are the effect they have: while the cursed seal is controllable, the unrefined enzyme produces uncontrollable rage in those exposed to it, including Jugo himself, and the effects cannot be controlled.

Tailed Beast Chakra
In the Naruto world, there are nine Tailed Beasts, which are ancient demons with immense chakra. During the Great Shinobi 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 ever 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 techniques. The hosts of the Tailed Beasts are called Jinchūriki, meaning "the power of human sacrifice". A human sacrifice is always required to seal a Tailed Beast.

The Jinchūriki can tap into the Tailed Beast's chakra for his or her own power. However, using such chakra can be harmful to the Jinchūriki, with the host's body and mind being influenced or even taken over by his or her demon. In the case of Naruto Uzumaki, when he uses the Nine Tailed Fox's chakra and reaches his Four-Tailed transformation, the chakra is so concentrated around his body that it constantly burns and repairs his skin right away, shortening his lifespan. But tapping in to such unnatural chakra is very harmful to the host, as the host's personality gets suppressed by the animalistic bloodlust of the Tailed Beasts and the intensity of chakra will harm the host if used for extended period of time.

Sage Arts Chakra
Sage Chakra, the chakra needed to perform Senjutsu (Sage Arts), is chakra that contains the energy found in nature itself. It's a powerful source of energy, able to grant a ninja increased strength, speed, and endurance for taijutsu, as well as enhancing the power of one's ninjutsus and genjutsus. Sage Chakra is created through the three-way mixing and balancing of one's physical energy and spiritual energy, as well as the natural energy from the atmosphere/air and terrain/ground. Since the three energies need to be equally balanced, the higher one's personal chakra capacity (physical energy and spiritual energy), the more natural energy they can add to the mix. Only those with a large chakra capacity can gather the natural energy needed for entering a powerful state called "Sage Mode". Also, only when a person remains "perfectly still", no longer disrupting the flow of nature around them, can they properly feel and harness natural energy. Remaining completely still for a period of time takes a great deal of concentration and patience, requiring a highly motivated state of mind.

There are side-effects. Those who don't remain perfectly still will begin drawing in too much natural energy. This will cause them to start turning into a toad, and eventually into stone. They will essentially become a part of nature. Jiraiya was able to create sage chakra and enter into Sage Mode, though he turned partially into a toad whenever he did so. Naruto has also learned to create sage chakra and enter into Sage Mode, though without developing any toad traits (besides the eyes). This indicates that he may have the potential of surpassing Jiraya when it comes to mastering Senjutsu.

Attempting to use Sage Mode during battle comes with some risks. To draw in natural energy requires the user to remain perfectly still, leaving them completely vulnerable to attacks. They can enter Sage Mode only if they have enough comrades that can protect them. If the user is alone, they would need to retreat from the battle for a while in order to gather the natural energy needed. Also, since the user is no longer creating sage chakra while fighting, Sage Mode can only be maintained for a few minutes, or until all the sage chakra is exhausted.