Expansion Jutsu is a technique used in the Naruto series that allows a user to enlarge objects or their own body. This ability can be utilized for various purposes, such as increasing the size of weapons or creating larger barriers for defense. The technique is often associated with characters who possess unique abilities, such as Orochimaru and Kisame Hoshigaki. By manipulating their chakra, users can control the scale of their expansions, making it a versatile tool in combat and strategy.