Sharingan

The Sharingan, which translates to Copy Wheel Eyes, is the Uchiha Clans Bloodline limit. This is the most desired and wanted bloodline throughout out the world of Naruto. The eye is said to have descended from the Hyuuga clan who possess the bloodline of the Byakugan eye...

The sharingan's most popular feature is the ability to mimic attacks. This eye is able to copy taijutsu, ninjutsu, and genjutsu with perfect accuracy. In order to use a copied jutsu, the user must have the needed skill to perform the technique. In addition, the eye is so focused, it is able to perceive movements even if those movements are faster than the user.

It is able to see the movement and flow of chakra as well as see through genjutsu depending on the user. The sharingan has many uses and grants the user extreme analytical abilities allowing them to detect and see thing with minimal effort.

The Sharingan has a unique brand of hypnosis that suggests movements and thoughts to the opponent. When focused and used with the rest of the eye, the user is able to perfectly duplicate it's opponents movements, even before the opponent makes any move. This makes it appear as if the user of the sharingan is able to see into the future.
Obtaining the Sharingan

The eye does not appear upon birth; instead, it will appear in a life-threatening situation where its power could save the user. After this initially happens, the user is then able to call upon the sharingan at will, any time.

The eye can also be transplanted from one user to the next. We learned from Kakashi's deceased comrade, Obito, that this is possible. However, transplanted eyes do not work as well in foreign users as it would in a natural Uchiha. With Sasuke and Itach, both appear to keep the eyes activated with very little effort; However, in Kakashi's case, he has had to restrain the use of his sharingan due to it consuming a great deal of chakra.
Pupils within the Sharingan eye

One of the visibly different things that makes the sharingan stand out would be the additional pupils that it has.

A. Motion Preceptors.
B. Copies all motion perceived.
C. Prediction Motion.
D. Ability to see Color.
E. Ties pupils together and allows the uder to see without confusion (Combining A-D).

Mangekyo Sharingan (Kaleidoscope Copying Wheel Eye)

Visually, this eye looks different, but similar to the Sharingan.The mangekyou Sharingan is a legendary ability which only a hand full of its' clan members have.

In a flashback, Itachi told Sasuke that there was a scroll located in their clan shrine that would reveal the true origin of the mangekyou. Long before Sasuke and Itachi's time, a story focused on Madara and his younger brother. The two of them were equals in every possible way, and were constantly competing to become stronger. In time, Madara became leader and one day he suddenly began noticing a strange abnormality within himself. The mangekyou has a very unique characteristic: from the day you awaken it, your eyes begin a slow descent into darkness. The more you use them, the quicker the process moves. This means that ultimately the user will go blind.

A. Motion Preceptors.
B. Copies all motion perceived.
C. Prediction Motion.
D. Ability to see Color.
E. Ties pupils together in able to see without confusion. (Combining A-D).

The left side of the mangekyou eye posesses the strongest Genjutsu. The right side of the Mangekyou eye posesses the strongest Ninjutsu.

Obtaining the Mangekyo Sharingan

Acquiring the Mangekyo is indeed controversial. Those who wish to have access to this eye must sacrifice alot, according to Itachi who murdered his best friend when his Mangekyo was activated. In Kakashi's case, he stated that many of the people he cared for died long before the series started, so his origin of the mangekyo is unknown.

Itachi's Mangekyo Sharingan

Itachi Uchiha obtained the Mangekyo Sharingan by murdering his best friend, Shisui Uchiha. With the Mangekyo in his possession, Itachi is able to use two of the most powerful jutsu of the Uchiha:

Tsukuyomi - This translates to "Moon Reader". When direct eye contact is made, Itachi can use this ability to transport his opponent into an illusionary world where they days in this world amount to seconds in the real world. Furthermore, because Itachi is a master of this world and technique, he is able to torture his opponents in the worst way possible, leaving them crippled in a state of mental anarchy.

Amaterasu - named from the goddess of sun, translates to "Shining Heaven". It is said that Amaterasu is the fire from hell which will never disappear until it burns everything in its path. It's a black flame that consumed even fire itself. It burns whatever the eye focuses on and the black flames will converge on exactly that spot. Then, they continue to burn until their target is completely eradicated, even if the target is flame itself.

Kakashi's Mangekyo Sharingan

While Itachi uses his mangekyo to destroy a target, Kakashi uses his to create a space-time warp that allows him to target any object and send it to another dimension, achieving the same result. Kakashi used this same technique against Akatsuki's Deidara, blowing off part of his arm sending it into the other dimension.