Amaterasu is a Mangekyō Sharingan dōjutsu, and the highest level of Fire Release. Said to represent the "Material World and Light", Amaterasu is the antipode to Tsukuyomi.
Amaterasu produces black flames at the focal point of the user's vision. In most situations, this makes Amaterasu impossible to avoid. However, if the target can move fast enough to prevent being focused on, Amaterasu will miss them when it's cast. Once created, it can continue burning for seven days and seven nights. The flames cannot be extinguished with water or any other normal methods; only the user can put the flames out. Said to be "the fires from hell" and to burn as hot as the sun itself Amaterasu burns any material — other flames included — until nothing but ash remains. Throughout the series some objects have shown some degree of imperviousness to the flames such as Gaara's chakra-infused sand, and Naruto's Version 1 chakra cloak.
Amaterasu does not ordinarily require hand seals to be performed, though Sasuke Uchiha once used the Tiger hand seal, which is common for fire techniques. This technique can also be sealed within the Sharingan of another person. Beyond mere offence, Amaterasu's flames can be used as a deterrent, with users surrounding themselves in its flames to discourage physical attacks. Use of this technique puts a great deal of strain on the user, usually causing their eyes to bleed. For all its lethal potential, Amaterasu burns fairly slowly, allowing targets to remove burning clothes before their body is caught ablaze or, if it's too late for that, remove the burning body part(s) before it spreads. Other defensive options are pushing the flames away, absorbing them, certain space–time ninjutsu, or being the jinchūriki of the Ten-Tails. While impractical as a defence, Amaterasu can also be sealed.