Disclaimer: I don't own Naruto!

Authors Note: The main purpose of this essay is to provide a concrete analysis of the Sharingan, since it is currently perceived to be one of the most overpowered abilities in the manga/anime (at least imho). As such, I am attempt to breakdown and describe the various aspects of it in depth. My main goal is for this to be available as a resource to other authors should they need it. World building essentially.

General Notes:

The Sharingan is one of the most feared types of Doujutsu. It is a Bloodline Limit specific to that of the Uchiha Clan of Konoha.

Primary Abilities:

The Sharingan can considered to be one of the most powerful doujutus, though it is also extremely focused and specialized towards the area of combat and battle. The Sharingan allows for far greater visual insight, makes chakra visible to the naked eye, and enhances the effects of any Genjutsu that the user chooses to employ.

The best known ability of the Sharingan is the improved visual insight that it grants. The user is capable of greatly enhanced vision, including precieving high speed movement that they would not be able to make out normally, as well as enhanced visual acuity; instantly picking up on the smallest details of picture from a single glance or noticing the slightest hints of movement. The degree of insight that the Sharingan possess is related to the number of tomoe that the eye has managed to evolve. An important note to make regarding the Sharingan is that the insight that it grants is limited to what the user is already capable of seeing, and despite the vast improvement in overall acuity, its improvement in perception is still limited to the users natural field of vision. Additionally, it does not enhance the distance that the user is capable of seeing, including the details from that range.

Like all doujutsu, the Sharingan is capable of seeing Chakra, although this ability does not take form until the eye is evolved to its second tomoe stage. In particular, the Sharingan is especially good at following the movements and flow of chakra, including when it is molded by hand seals and focused to specific areas of the body for enhancement of speed, power, or resiliance. Finally, a three tomoe Sharingan is also capable of perceiving the different types of elemental chakra as separate colors.

The final aspect of the Sharingan is its ability to boost Genjutsu, making them far more power and effective. This is because of its ability to see the exact flow of chakra and precisely target the Genjutsu against them. They are also capable of using a unique form of hypnosis based Genjutsu that utilizes the tomoe in their eyes rather than hand seals.

Secondary Effects:

An activated Sharingan also focuses chakra in the area of the brain associated with memory. This boost in the mental process gives the user of the Sharingan an eidetic memory for anything that is seen with an activated Sharingan. It is this ability, along with the fact that it is capable of perfectly seeing the flow of chakra or muscle movements for most techniques that allows them to memorize and copy opponents techniques. This perfect recall also extends to such areas as muscle memory as well, allowing Taijutsu techniques to be memorized and copied perfectly as well, in addition to most conventional Ninjutsu and Taijutsu techniques. With the exception of muscle memory however, the eidetic memory is only possible when the Sharingan itself is activated, although skilled ninja are capable of focusing chakra to that area of the brain without actually activating the Sharingan.

Drawbacks:

The main drawback to the Sharingan is the fact that it has a far higher chakra cost than either of the other Doujutsu. While the cost of activating and maintaing the Sharingan are relatively high, a member of the Uchiha Clan is capable of mitigating that to some extent. Utilizing any of the more advanced abilities of the Sharingan beyond that of improved insight drains chakra at a far greater rate, even for a Uchiha. This advanced functions include the shifting of sight beyond that of normal range so that chakra can be precieved, any hypnosis-type Genjutsu, effective movement prediction, or the copying of techniques.

A far more minor drawback that relates to the ability of the Sharingan to copy techniques is the fact that any of the techniques lack the verstility that would be possible if the user had actually learned it. The reason for this is that any techniqes that have been copied can only be followed exactly, and not be improvised from in the middle of. It is possible to chain multiple copied techniques together still, but the technique itself cannot be altered in any way while it is being implemented. Additionally, any copied Ninjutsu and Genjutsu may only be used when the Sharingan is activated, although copied Taijutsu may still be used at any time by the user. These limitations may be overcome if the possesser of the Sharingan takes the time to familarize and train with any copied technique, although this essentially amounts to relearning the technique by hand.