Hand signs are different positions and arrangements of the fingers that the ninja needs to regulate chakra and use techniques. They are used to perform Nin- and Genjutsu. Only after the completed forming of the hand signs the respective Jutsu is actually performed. However, as the story progressed, hand signs became less and less important. In the beginning they were a sign for particularly complicated techniques but later, they were used very rarely.
To be able to perform Nin- or Genjutsu, chakra is required. This chakra is regulated with the help of the hand signs. Jutsu, which requires several hand signs, can be stronger or more efficient because the regulation requires more hand signs and, therefore, more chakra.
Ninja, such as Sakura, for example, which can regulate the chakra correctly and also perfectly form hand signs, lose almost no unnecessary chakra. In contrast, if a hand sign is performed incorrectly, the chakra used will be less well regulated, and the user will waste chakra unnecessarily. Furthermore, the applied Jutsu loses extremely in strength or cannot be executed correctly at all.
There is no regulation necessary to use Taijutsu because Taijutsu usually does not require the use of chakra. For Naruto, it is tough to regulate chakra without losses because he doesn’t have the chakra of the Kyubi properly under control, and according to Kakashi, it additionally even disturbs Naruto’s own, normal chakra flow. This means that it prevents him from regulating his chakra perfectly, and he also has to apply proportionally more chakra when using Jutsu.
The 12 Hand Signs
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Special Hand Signs
In addition to these twelve finger signs, there is a whole series of other, different finger signs. They are used in special situations and for special Jutsus.
For some Jutsus, hand signs are also used that differ from the standard signs. Most of them are used for the use of Hiden, such as in Ninpo: Shintenshin no Jutsu and the Shinranshin no Jutsu of the Yamanaka clan.
In Shintenshin no Jutsu, the hands are placed parallel to each other, and in Shinranshin no Jutsu, they are held mirror-inverted at a slight distance from each other.
Haku is the only known ninja who is able to form hand signs with only one hand. Additionally, he uses special hand signs for the use of his Kekkei Genkai.
For Hijutsu: Makyo Hyosho, he needs a hand sign where the hands are held similar to Tora. However, it is special that Haku lets his index fingers pass-through between the middle fingers and makes them meet again.