Sharingan

It is the Uchiha’s kekkei genkai, which grants a good number of abilities to the person who develops them fully, it is one of the four great dōjutsus and is known as “The Copy Eyes”. The Sharingan has three levels of evolution, with the third level being the strongest.

Abilities
In the first level the user gains a massive increase of perception, being capable of reading lips, copying movements perfectly and memorizing everything perfectly with every detail, with this level is possible to copy seals from a jutsu or even copying taijutsu styles.

With the second level the perception and memorizing abilities are increased even more, being capable of seeing things in slow motion and predict the opponent’s next move, copying their movements and confusing them.

When the third level is reached the user is able to see chakra in colors, being able to distinguish it and seeing it through smoke, it’s also possible to see irregularities in a chakra system, meaning it’s possible to detect genjutsus. Since the user can now see chakra, they can see how chakra behaves in a jutsu, meaning the user can copy any ninjutsu or genjutsu.

Evolution
If any bearer of a mature Sharingan receives pure chakra in their system or if they have Uchiha and Senju/Uzumaki blood, it's possible to awaken the kekkei tōta of the Uchiha Clan, the Rinnegan.