The Advance Bloodline Limit is a special ability known to only a particular group of individual. That special ability can only be passed down to members within the same family, through different generation, by the process of genetic (DeoxyriboNuclecAcid) reshuffling. Clan tend to have advance bloodline but not all clan. Advance bloodlines can only be pass down within the family bloodline or within a clan. Those bloodline carry advance ability that aid them in combat.
Sharingan
Translation: Wheel Eye
Clan: Uchiha Clan
Description: 2 red pupil, 1 to 3 fire rings around pupil
The Sharingan is a special ability found in the pupil of select members of the Uchiha clan. It is a pupil characteristic which is said to have been passed down from the Hyuuga's Byakugan, and then, with time, evolved. The Byakugan is also an advanced bloodline of the Hyuuga's, but although it is so closely related to the Sharingan, the Byakugan is far stronger. It is also said that possibly, the Uchiha's original traits are from the Hyuuga clan, which also explains the Sharingan's existence.
The Sharingan, as said before, is a pupil characteristic, so it is not considered a ninjutsu. Although it uses up chakra when used, this advanced bloodline requires no hand seal to be performed; the user just focuses some chakra on his eyes, bringing the Sharingan to the surface. Also, note that this ability does nothing useful by itself; it needs to be combined with other Jutsus to work effectively. This means that the Sharingan can only be used properly by people who know many diverse types of fighting. The Sharingan has many abilities, but it's main one is the ability to copy every Nin, Gen, and Tai Jutsu seen by it. This means that in every fight the Sharingan is used, the more techniques are learned. Also, this doesn't require the user to want to learn the technique. It is like a defense mechanism, which operates once the attack commences. Another of the Sharingan's abilities is seeing through illusions. For example, Bunshins, or even Kage Bunshins are no problem for the Sharingan. It can see them all as chakra sources, and only the real one looks normal.
It is also said that the Sharingan can see the future; however, this is a false statement, as Zabuza explains it. According to him, the Sharingan cannot see the future; instead, it uses a series of steps to create the illusion that the ninja can foresee the future, making his opponent think so. The ninja first uses his eye to scare the opponent; he then uses a very smart hypnotist genjutsu, which gives the enemy the illusion that the ninja can see the future. Following that, the enemy is really scared, and starts performing a jutsu; the Sharingan then copies all of the movements, so it looks as if the user can predict his movements by moving the same way as the enemy. Next, through the hypnotic jutsu, the Sharingan suggests a jutsu to the enemy. Finally, since the user knows what seal will be performed, he just copies the movement with his Sharingan, scaring the enemy even more!
Against the Sharingan, virtually all Jutsus are useless. However, a person with an advanced bloodline, or a Taijutsu user, is the Sharingan's worst enemies. Most Taijutsu shinobi's use speed on their advantage. This means that, even if the Sharingan can see the movement, it still gives no time for the ninja to react, making it useless. This also goes for advanced bloodline users, who use speed in their advantage too. However, a Taijutsu ninja would be tougher to beat, mainly because of the lack of Chakra and hand seal use.
Since physical attacks mostly don't need chakra, the Sharingan can't predict them that well. Moreover, since no chakra is needed, no hand seal is needed, thus giving the opposing ninja a chance to strike at once, without giving a chance of copying to the Sharingan. Long story short, the Sharingan is pretty useless against speed, but really useful against Ninjutsu users.
