Fūinjutsu

are a type of jutsu that seal objects, living beings, chakra, along with a wide variety of other things within another object.

Trivia

 * 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 their sealing techniques.
 * Given her red hair, skill in sealing techniques, and the history of the Uzumaki clan, Honoka was suspected to be a member. A book in an old abandoned house on the island even mentions finding a survivor of a certain clan of ninja.She used the Beast Sealing Technique.
 * Sai used an interesting jutsu called Sealing Technique: Tiger Vision Staring Bullet