What is eye of Sharingan?

Sharingan or known as "Copy Wheel Eye" which appears in some members of the Uchiha clan is Naruto series. Sharingan is one of the three great dojutsu, along with the Byakugan and the Rinnegan.

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 tomoe around the central pupil, varying between users. The wielder of the Sharingan, through continued use and training, evolves it further which involves gaining more tomoe, up to a maximum of three per eye. As the Sharingan develops, the user gains heightened abilities.

The first of the Sharingan's powers is being able to see the flow of chakra. This enable the user detect enemy in invisible and to detect gejetsu or illusion.
The Sharingan's second-most prominent ability grants the user an incredible clarity of perception, allowing them to easily recognize genjutsu and different forms of chakra. This enable the user to predict enemy jutsu either Fire, Wind, Water or Earth jutsu.

The Sharingan's third and most well-known ability is that it grants the user the ability to memorize any technique that he or she witnesses. This enable the user to copy enemy jutsu and use it in battle but some technique cant be copy and are called type s jutsu. This jutsu are been created originally by the user.

Usually sharingan user stuck at 3 tomeo at 1 eye. This is maximum for normal sharingan user but it sharingan can still be evolve. This evolution required certain condition that make it forbidden. It required a life of the loves one the awaken Mangekyou Sharingan. Mangekyo Sharingan look differ from normal Sharingan through its appearance, which changes the form of the tomoe seal. Unlike the Sharingan, it has a different appearance between the users, as a kaleidoscope
never looks the same.

1. Uchiha Itachi Initial Mangekyou (Kaleidoscope). Form This variation is the Mangekyou (Kaleidoscope) form while not fully changed. Sasuke initially caught a glimpse of this version of Itachi's Mangekyou which differed from his later version.

2. Uchiha Itachi Mangekyou (Kaleidoscope) Form. This is the rare Mangekyou (Kaleidoscope) form which is said to only appear in a few Uchiha members. Uchiha Itachi was able to finally master this form during the period he killed his clan. In this form Itachi is able to use the Amaterasu and Tsukuyomi Doujutsu techniques.

3. Hatake Kakashi Mangekyou (Kaleidoscope) Form. This Mangekyou Sharingan form was revealed by non-Uchiha clan member Hatake Kakashi. Whether this form is due to Kakashi or some inheritance from what Uchiha Obito was capable of is unknown. Using the eye, Kakashi can use a technique which appears to collapse space in around a focus point and transport it to another location.

4. Uchiha Madara Mangekyou (Kaleidoscope) Form. This Mangekyou Sharingan form was attained by Uchiha Madara. After developing the Sharingan, Madara and his younger brother trained against one another and eventually awakened their own version of the Mangekyou. The use of these eyes increased the brothers' strength and allowed them to take over leadership of the clan. Unfortunately the usage of the eyes lead Madara to lose his vision.

5. Madara's Brother's Mangekyou (Kaleidoscope) Form. This Mangekyou Sharingan form was attained by Uchiha Madara's younger brother. After developing the Sharingan, both brothers trained against one another and eventually awakened their own version of the Mangekyou. The use of these eyes increased the brothers' strength and allowed them to take over leadership of the clan.

6. Uchiha Madara's Eternal Mangekyou (Kaleidoscope) Form. Unable to accept being blind, Madara did everything he could to regain his vision. A desperate Madara eventually removed his brother's eyes to use as his own. As a result, Madara awakened a new more powerful set of eyes which allowed him to see the light once again. This new eye form would combine the look of both he and his brother's Mangekyou Sharingan.

7. Uchiha Sasuke's Mangekyou (Kaleidoscope) Form. Itachi sought to protect his younger brother from Uchiha Madara. To that end he used a jutsu to implant his Mangekyou and its techniques into Sasuke. When Sasuke's Mangekyou was initially activated, it resembled the version seen in Itachi. Later Sasuke's Mangekyou took on this form. It is unclear if this is the Eternal Form of Mangekyou, combing the form of Itachi's Mangekyou and that of Sasuke's, or if it is simply Sasuke own singular Mangekyou form alone.