Fūinjutsu (封印術, Literally meaning: Sealing Techniques) are a type of jutsu that seal objects, living beings, chakra, along with a wide variety of other things within another object. Fūinjutsu can also be used to restrict movement or unseal objects either from within something or someone.
The presence of a seal is marked by the appearance of formations of technique formulae, kanji, or else other kinds of symbols (likewise with Summoning Techniques).
A unison of barrier ninjutsu and fūinjutsu is referred to as a "Sealing Barrier" (封印結界, Fūin Kekkai).
- An imbalance is created when an odd-numbered seal is placed on top of an even-numbered seal and vice-versa.
- The shinobi from Uzushiogakure in the Land of Whirlpools were specialists in the art of fūinjutsu, to the point that their nation was eventually destroyed due to the fear others had of these techniques.