Amaterasu

Amaterasu is the highest level Fire Release technique, and is noted to be Itachi Uchiha's strongest ninjutsu which stems from his dōjutsu. It is said to represent the, the antipode to Tsukuyomi — a genjutsu of similar power and a fellow Mangekyō Sharingan dōjutsu. Use of the technique puts a great deal of strain on the user, usually causing his eyes to bleed.

Overview
The jet-black flames of the Amaterasu, said to be "the fires from hell" that are as hot as the sun, ignite at the focus of the user's vision. Though the flames have been stated to be unavoidable, Amaterasu has been avoided a few times; Sasuke Uchiha managed to dodge the flames when Itachi tried focusing on him, though Itachi did not actually want to kill him and managed to hit Sasuke shortly after regardless, and A using his Lightning Release Armour enhanced Body Flicker Technique avoided a short-range Amaterasu launched at him by Sasuke in an instant.

The flames are capable of burning through mostly anything in their path, even smothering regular fire techniques with ease. Amaterasu is said to never stop burning; even when whatever is caught by the Amaterasu is completely reduced to ash or destroyed, it can still continue burning for seven days and seven nights. It cannot be extinguished with water or any other normal methods. The only thing that the flames have failed to burn into or through is Gaara's chakra-infused sand. However, the flames burn fairly slowly, sometimes allowing anyone struck by Amaterasu an opportunity to remove whatever clothing or body parts have been caught ablaze. Nagato was able to deflect the flames from his body using Shinra Tensei. Jiraiya was also able to seal the flames with the Fire Sealing Method.

Manipulation
Users of this technique have shown the ability to manipulate these flames to some extent. Itachi was able to quell the flames during his battle with Sasuke, something as Zetsu noted was done to protect Sasuke's eyes. Sasuke himself would later quell the flames during his battle with Killer B, after Karin had accidentally been caught in the flames. Furthermore, the Uchiha derived an ability known as Blaze Release through which they could manipulate the flames to serve as not only an offensive ability but a defensive one as well. This can also be applied to Susanoo's weapons, to increase their lethality.

Influence
As from the ancient Japanese myth and religion of Shintō, Amaterasu, Tsukuyomi, and Susanoo are all gods. When Izanagi washed his face after escaping the underworld his left eye became the Sun Goddess, Amaterasu.