"Sharingan" or "the eyes that sees all" is the dojutsu kekkei genkai of the Uchiha clan.
It is part of the three great dojutsu which include the Byakyugan and the Rinnegan.
Sharingan is awakened and evolved through an overwhelming amount of emotions.
As the level of Sharingan increases, the power of the bearer also increases. Sasuke Uchiha is the last surviving member of the Uchiha clan.
He went through an overwhelming amount of pain which has evolved his Sharingan.
Let’s take a look at the various stages of Sasuke’s Sharingan
1 Tomoe Sharingan
Sasuke’s Sharingan actually awakened when he saw the massacre of his entire clan.
Upon seeing such a brutal scene and his elder brother accepting to have killed them, Sasuke’s Sharingan was awakened.
Due to his young age, he collapsed with the heavy usage of chakra.
Activation of 1 Tomoe Sharingan
Sasuke had got the Sharingan after the massacre of his clan. But he could not use his Sharingan for a long time after that.
This was because of the brutal trauma that he endured during the night of the massacre.
He subconsciously had blocked the painful memories and also the awakening of the Sharingan.
It was in the battle against Haku that he activates the Sharingan again.
Haku using his Kekkei Genkai could throw the needles at an enormous speed that could prove fatal.
To save Naruto and himself, Sasuke was able to reactivate his 1 tomoe Sharingan.
It helped him to match the speed of the needles and counterattack to save themselves.
2 Tomoe Sharingan
Sasuke’s 2 tomoe Sharingan got activated during the chunin exams.
While fighting against Orochimaru, Sasuke halts because of intense fear.
Seeing Naruto fight the powerful opponent, gave him courage.
He remembers a few words about Itachi and his life goal at that time. Because of these intense emotions, he awakened 2 tomoe Sharingan.
The power of his Sharingan can be seen in his fight against Gaara.
Sasuke copies the taijutsu movements and speed of Rock Lee within a month of training.
He also learns a new Jutsu- Chidori during this one month with the help of his 2 tomoe Sharingan.
3 Tomoe Sharingan
Sasuke’s 3 tomoe Sharingan is awakened when he fights Naruto for the first time in the valley of the end.
In the middle of the fight, there was a few moments of vulnerability between them.
Naruto told Sasuke that he considers him a brother. But Sasuke’s desire to be more powerful outweigh his bond with Naruto.
This clash of intense emotions gave rise to his 3 tomoe Sharingan.
Sasuke awakened his Mangekyo Sharingan after he killed his brother Itachi.
Mangekyo Sharingan comes at a cost of losing a loved one and gives many powers to the one bearing it.
After learning the truth about Itachi, Sasuke went through a lot of pain that gave rise to his Mangekyo.
With this, he infiltrated the five Kage summit and killed Danzo. He could use Susanoo and Amaterasu with the help of his eyes.
Eternal Mangekyo Sharingan
With the excessive use of Mangekyo Sharingan comes a downfall- the user losing their sight. As a result, Sasuke becomes nearly blind.
If an eye of a relative is transplanted, then this side effect is gone.
Hence, Obito transplants Itachi’s eyes when Sasuke asks for it.
Thus, Sasuke developed the eternal Mangekyo Sharingan which is regarded as the highest form of Sharingan.
The user is able to use the powers of Mangekyo Sharingan extensively without any shortcomings.
Thanks for reading!