Sharingan

The is a Kekkei Genkai, which appears in some members of the Uchiha clan. Some think that it was derived from the Byakugan. Although it consumes chakra while active, the chakra levels that Uchiha must exert is so insignificant that they can keep it active near-constantly.

Stages
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, evolves the Sharingan which involves gaining tomoe. As the Sharingan evolves the user gains new abilities until the maximum of three tomoe is achieved. The only level up from there is the Mangekyo Sharingan, which is gained by the loss of someone close to the user.

Abilities
shaaringan o itachi tem rinegan e sharingan ele por enquanto ele e o mas forte do naruto
 * itachi e tao bondoso que cria um doujutsu para irmao dele kimimaro

Receiving the Sharingan
Unlike the Byakugan, the Sharingan does not automatically appear from birth in a user; instead, the user has to awaken it. After this first appearance, the user can then call up the Sharingan any time he or she pleases. It is possible to transplant Sharingan eyes from one person to another, as occurred with Kakashi and his deceased comrade Obito Uchiha. Kakashi's Sharingan cannot be deactivated. Because of this, and because using the Sharingan requires much more chakra from him than it does an Uchiha, he usually covers it to conserve chakra.

Transplanting the Sharingan eyes from a living or deceased Uchiha is the only way to avoid the loss of sight over time from the Mangekyo Sharingan. The user is then said to have an 'Eternal Mangekyo Sharingan'.