Sharingan

The is a dōjutsu kekkei genkai, which appears in some members of the Uchiha clan,with the exception of Kakashi Hatake and Danzō Shimura though they had them transplanted. It is one of the, along with the Byakugan and the Rinnegan. The Sharingan is also called, because of the many abilities it grants the user.

Abilities
The Sharingan's abilities consist of two parts: the and the. The first of the Sharingan's powers is being able to see the flow of chakra. The Sharingan itself gives colour to chakra, allowing the wielder to differentiate them. They are also able to tell if a person is under a genjutsu because the person's chakra flow would be irregular. The Sharingan's second-most prominent ability grants the user an incredible clarity of perception, allowing them to easily recognise genjutsu and different forms of chakra, though not to the same extent as the Byakugan. This also allows the user to pick up on subtle details, enabling them to read lip movements or mimic something like pencil movements. As the Sharingan evolves, gaining more tomoe seals, this ability extends to being able to track fast-moving objects before finally giving some amount of predictive capabilities to the user, allowing them to see the image of an attacker’s next move from the slightest muscle tension in their body and counterattack or dodge without any wasted movement. However, even though the user may be able to see an attack or know it is coming, their body may not always have time to react.

The Sharingan's third and most well-known ability is that it grants the user the ability to memorise almost any technique that he or she witnesses, apart from other kekkei genkai techniques. The user can memorise ninjutsu, genjutsu, and taijutsu with near perfect accuracy, allowing the user to use the techniques as their own, or even modify them to create their own new techniques, much like Sasuke Uchiha's Lion Combo. In order to reproduce a copied technique, however, one must have the necessary skill or ability to perform them. A prime example is Rock Lee's brand of taijutsu. While Sasuke was able to copy some of Lee's moves, they put a much more significant strain on him since he hasn't trained nearly as much as Lee has. In addition to physical skill and kekkei genkai techniques, the Sharingan cannot reproduce techniques dependent on other factors, such as summons that the user has not signed a contract with.

The Sharingan's final commonly-used ability is capable of inducing a unique brand of hypnosis that involves suggesting actions and thoughts to the opponent through genjutsu cast by simple eye contact between both parties. More advanced Sharingan users can take the hypnosis ability even further to the point where a powerful summon like Manda or even a tailed beast may be controlled. When this was used against Manda and Kurama, their eyes took on the tomoe pattern of the users' Sharingan while under hypnotic influence.

The hypnotic ability coupled with the other aspects of the Sharingan can make the user appear as if they can "see the future". First, the user must perfectly mimic every move their opponent makes and possibly their thoughts and words through careful observation. Then, they suggest an action to the opponent such as hand seals for a technique that the opponent and Sharingan user already know and copy that. With these things done, the user can complete the action even before the opponent does, possibly using the Sharingan's genjutsu to confuse or delay them. As with other genjutsu, genjutsu cast by the Sharingan are capable of putting an opponent to sleep, inducing paralysis, replaying memories to someone else, or creating various illusions to deceive someone. The potency of the Sharingan's illusion is dependent on the user's knowledge and skill with implementing genjutsu. Two Sharingan users are also able to free each other from other forms of genjutsu by first using genjutsu on each other, allowing them to enter their comrades mind and free each other from the genjutsu.

In addition, more rarely used by the Uchiha clan, the Sharingan can allow the user to perform two very powerful and unique genjutsu: Izanagi and Izanami, which alters or decide one's destiny, respectively. Using Izanagi, the user can warp reality for a short amount of time, changing reality into illusion and illusion into reality. Although to make use of this technique to its full extent, the user must have the DNA of both the Uchiha and Senju clan. Izanami, on the other hand, is a genjutsu that traps the victim in an illusory world disregarding their five senses. However, both techniques have been labelled kinjutsu, because use of either causes the eye that performed Izanagi or Izanami to close forever.

Although the Sharingan consumes the user's chakra while active, the chakra levels that the user must exert is so insignificant that they can keep it active constantly. In fact, Itachi Uchiha was so masterful of it, he was able to keep it active for most of the time, only once deactivating it after using Tsukuyomi on Sasuke and Kakashi, as well as Amaterasu to escape Jiraiya due to exhaustion. However, when a Sharingan is transplanted to a non-Uchiha, the chakra drain is significant, leading them to cover it up when not in use. This seems to be circumvented by acquiring Senju cells in order to boost their vitality.

Stages
The Sharingan is not automatically activated in the user by birth. It is only first unlocked under some stressful or emotional condition after which the Sharingan may be used freely. When the Sharingan is first activated by a user, it has a different number of around the central pupil, varying between users.

The wielder of the Sharingan, through continued use and training, changes its form further, which involves gaining more tomoe up to a maximum of three per eye. As the Sharingan develops, the user gains heightened abilities through the heightened ocular sense. For example, they can at least copy hand movements with one tomoe, predict a person's movement and copy techniques with two and completely use the Sharingan's abilities when it is fully matured.

Receiving the Sharingan
As already mentioned, the Sharingan needs to be activated by the user when they are faced with a difficult circumstance or placed under emotional stress. After its first appearance, the user can use the Sharingan any time he or she pleases. It is also possible to transplant Sharingan from one person to another, as occurred with Kakashi Hatake, who received his left eye's Sharingan from his dying comrade, Obito Uchiha. Because of this, Kakashi's Sharingan cannot be deactivated, and as using the Sharingan requires much more chakra from him than it does from an Uchiha clan member, he usually covers it with his headband to conserve chakra. Also, Kakashi needs to rest for a longer period of time after using his Sharingan extensively in battle. In a similar way, Danzō Shimura had a Sharingan instead of his normal right eye, that he gained from Shisui Uchiha, which he kept hidden under his bandages. Danzō also possessed ten Sharingan in his right arm, which is kept sealed until he needs them. It is also possible to transplant it to animals, as Itachi did with Shisui's Sharingan with one of his crows.

Mangekyō Sharingan


The Mangekyō Sharingan gives the user access to several powerful techniques, including the powerful fire technique Amaterasu, the use of Susanoo and the almost unbreakable genjutsu Tsukuyomi. The Mangekyō Sharingan however erodes the eyesight of its users, eventually causing blindness, which can be prevented by obtaining another pair of Mangekyō Sharingan from a sibling. The new Sharingan is dubbed the.

Beyond Eternal Mangekyō Sharingan
The Eternal Mangekyō Sharingan has been shown to be able to progress to the Rinnegan through unknown means. This was displayed by Madara Uchiha who noted that he was able to awaken this dōjutsu shortly before his death, which contrary to popular belief, did not occur at the battle at the Valley of the End. This fact was written on the Stone Monument of the Uchiha located in the Naka Shrine.

Trivia

 * Some characters believe that the Sharingan was somehow derived from the Hyūga clan's Byakugan. It is however revealed by Tobi that the Sharingan is evolved from the Uchiha Clan Ancestor's dōjutsu, which is evolved from the Rinnegan. It is unknown where or even if the Byakugan fits into this lineage.
 * The Sharingan and its derived forms have shown the ability to spin, true to its name of "Copy Wheel Eye".
 * In the anime, two of Sasori's hundred puppets are seen with what appears to be Sharingan eyes.
 * No female has been observed as a Sharingan user.