Hand seal (Earth-2356)

Hand seals are used to perform many Force techniques other than body techniques. Invented by Indra Ootsutsuki, they are designed to aid people in properly summoning and moulding midi-chlorians necessary to tap into the Force and perform a technique. There are different sequences of hand seals for every technique, requiring memorization.

While techniques may require a number of hand seals to work, a skilled Jedi or Sith can use less or even one to perform the same technique. An example of this is the Water Release: Water Dragon Bullet Technique, which requires a total of 44 hand seals to activate. Tobirama Senju, the second Grand Master of Coruscant's Jedi Order, only needed to use one hand seal to complete the technique, a testament to his skill. As time went on, Darth Vader managed to master the Chidori and Fire Release techniques to the point of needing only one hand seal to invoke it. By reading the hand seals of the opponent, a Force user can predict the nature of the technique to be performed, which is virtually unavoidable if read by the Sharingan.

Basic hand seals
There are twelve basic seals.
 * Ne: This hand seal was commonly affiliated with the special Shadow Techniques of the Nara Clan.
 * Ushi
 * Tora: This hand seal is commonly affiliated with Fire  and Earth Release.
 * U
 * Tatsu
 * Mi: This hand seal is commonly affiliated with Earth, Lightning, and Wood Release.
 * Uma
 * Hitsuji
 * Saru
 * Tori: This hand seal is commonly affiliated with Wind Release.
 * Inu: This hand seal is commonly affiliated with Water Release  and Ice Release.
 * I

Source

 * https://naruto.fandom.com/wiki/Hand_Seal.