Fuuinjutsu is a form of ninjutsu in the Naruto series that involves sealing techniques. These techniques are used to contain or restrict objects, creatures, or even chakra. Fuuinjutsu can be applied in various ways, such as sealing away powerful entities or preventing the use of certain abilities. The effectiveness of Fuuinjutsu often depends on the skill of the user and the complexity of the seal. Some seals can be simple, while others require intricate designs and specific materials. Notable users of Fuuinjutsu include Tobirama Senju and Minato Namikaze, who have created powerful sealing techniques in the series.