The Summoning Technique allows the user to transport a target to their location.
Before an animal can be summoned, a prospective summoner must first form a contract with the animal and/or its species. In the case of the toads, the contract is a scroll that the summoner signs their name to using their own blood and further marks with the fingerprints of one of their hands. Orochimaru has the snakes' contract tattooed to his arms, which he smears with blood each time he wants to perform a summoning. Sasuke Uchiha has two contracts (snakes and hawks), something that no other shinobi has demonstrated. Contracts remain active even after death, allowing those revived with the Impure World Reincarnation to perform summons they established when they were alive.
To actually summon an animal, users apply some of their blood to the hand they signed the contract with. Usually they bite one of their fingers to accomplish this, but blood from injuries elsewhere on their body can also be used. They press the hands' five fingers to the ground and channel chakra to the hand, summoning the animal to that location. The amount of chakra gathered in the hand determines the size and number of animals that are summoned: if too little chakra is offered, only a small, young animal will be summoned; by offering large amounts of chakra, multiple adult animals can be summoned simultaneously. Two people who have signed the same contract can pool their chakra to summon especially large animals. If an individual has access to the blood of someone who has signed an animal's contract, they can use the blood to summon the animal; the individual will need to provide their own chakra, however.
Animals are typically summoned in order to lend assistance to their summoner, either by carrying out tasks or joining them in combat. Summoners will sometimes use their summons as a base for other jutsu, as with Summoning: Food Cart Destroyer Technique and Summoning: Quick Beheading Dance. But summoned animals are not actually required to do anything and may choose instead to harm their summoner; Manda routinely threatens to kill his summoners. Animals can even refuse their summoner's attempt to summon them by sending another of their species in their place. Animals are not summoned indefinitely and will return to wherever they were summoned from when they tire out and/or enough time has passed.
Having the Rinnegan allows the user to circumvent several of the Summoning Technique's normal limitations. Using the Animal Path, Rinnegan users can summon dozens of different animals (and even people) without the need for blood. It is only with the Rinnegan that the Demonic Statue of the Outer Path can be summoned, whose actions are directly controlled by the Rinnegan user. Hagoromo Ōtsutsuki – the originator of the Rinnegan – is able to summon five people and the nine tailed beasts from Kaguya's Dimensions, though he needs the chakra of seventeen dead Kage to do so.
Known Summoning Domains
- "Kuchiyose" (口寄せ, Literally meaning: drawing in to speak) refers to the practice of allowing spirits to possess one's body and speak through it.
- A technique formulae (術式, jutsu-shiki) is produced at the hand's location when a summoning is performed. Like with seals, these formulae are a random assortment of Kanji, Hindi script, and other symbols.
- Animals can summon those who have signed contracts with them using the Reverse Summoning Technique.
- Kurama can apparently identify who is trying to summon it, something other summons have not been able to do. Similarly, any person who has summoned Kurama must continually provide their own chakra in order to keep it under their control.
- In the anime, Shiromari is summoned for a fifty year period because of a scroll left by its summoner before they died. When the scroll was destroyed, Shiromari was finally able to return home.
- In the anime, attempting to summon an animal without first signing a contract teleports the user to the home of the animal they have a natural affinity for.  Later, attempting to do this simply results in failure.
- ↑ Rin no Sho, page 182
- ↑ Naruto chapter 477, page 9
- ↑ Naruto chapter 92, page 18
- ↑ 4.0 4.1 Naruto chapter 165, pages 18-19
- ↑ Naruto chapter 477, page 9
- ↑ Naruto chapter 530, page 14
- ↑ Hyō no Sho, page 163
- ↑ Naruto chapter 430, pages 2-3
- ↑ Naruto chapter 650, page 6
- ↑ Naruto chapter 363, page 10
- ↑ Naruto chapter 124, pages 9-11
- ↑ Naruto chapter 214, pages 15-17
- ↑ Naruto chapter 171, page 2
- ↑ Naruto chapter 634, page 1
- ↑ Naruto chapter 642, page 8
- ↑ Naruto chapter 606, pages 12-14
- ↑ Naruto chapter 690, pages 14-17
- ↑ Naruto chapter 686, page 1
- ↑ Naruto chapter 409, page 9
- ↑ Naruto chapter 561, page 11
- ↑ Naruto chapter 96, pages 4-5
- ↑ Naruto chapter 502 page 13-17
- ↑ Naruto episode 194
- ↑ Naruto: Shippūden episode 127
- ↑ Boruto episode 4