A Summoning Technique is a space–time ninjutsu that allows the summoner to transport animals across long distances instantly.
One method involves just hand signs and blood. With this, before an animal summoning can be performed, a prospective summoner must first sign a contract with a given species. The contract can come in the form of a scroll or a tattoo, which is signed in the contractor's own blood and once signed is valid even after the contractors death. After this, they need only perform the hand seals, offer an additional donation of blood, and use the same hand they signed the contract with to summon the creature. The amount of chakra used during the summoning determines how big the summoned creature can be. In the anime, it was shown that if a user attempts to summon an animal without first signing a contract, the user will be teleported to the home of the animal they have a natural affinity for.
An alternate form of summoning is to just use a scroll without any hand-signs. In this case hand signs are not necessary, with chakra not even being necessary sometimes. By using this method, one can summon creatures with whom one does not have a contract with.
While most summoners have only been shown capable of summoning one type of creature, Pain (through the Animal Path) has been seen summoning several different animals and even people. Pain does not provide a blood offering when performing a summon. Sasuke Uchiha has summoned snakes and hawks at different points, but unlike Pain he can apparently only summon one species at a time. The ability to perform a summoning can be removed with the Contract Seal.
When an animal is summoned it is transported from its place of residence to the summoner's location. Once summoned, the animal can perform a task or help the user in battle. The summon is not required to help the user, and may be more of a hindrance than an ally. In addition, summons are able to summon their summoner. They may also wear a forehead protector, suggesting a loyalty to only one village.
Summoning can serve as a base for other jutsu, as is the case with Summoning: Food Cart Destroyer Technique and Summoning: Quick Beheading Dance. In these cases, summonings may not be restricted to creatures, as Orochimaru shows by summoning corpses and defences.
Items can be "summoned" from scrolls. Because the items are not summoned from anywhere, instead only being released from storage, no blood is needed and thus it is not a conventional summoning. Characters have on occasion been shown summoning weapons such as kunai and giant shuriken, sometimes without hand-signs.

Users
Minato Namikaze (Toads)
Kakashi Hatake (Ninken)
Might Guy (Ningame)
Orochimaru (Snakes)
Jiraiya (Toads)
Naruto Uzumaki (Toads)
Hiruzen Sarutobi (Monkey King: Enma)
Tsunade (Slugs)
Kidōmaru (Kyodaigumo)
Tayuya (Doki)
Temari (Kamatari)
Kabuto Yakushi (Snakes)
Anko Mitarashi (Snakes)
Sasuke Uchiha (Hawks, Snakes)
Hanzō (Ibuse)
Nagato (Demonic Statue of the Outer Path, Konan, Six Paths of Pain)
Shima
Danzō Shimura (Baku)
Madara Uchiha (Nine-Tailed Demon Fox)
Kisame Hoshigaki (Shark)
Motoi (Owl)
Suzumebachi (Bees)
Amachi (Umibōzu)
Ruiga (Piranha School, Shark)
Gennō (Giant Ninja Bird)
Tonbee (Bats)
Kandachi (Conch King)
Hiruko
Ichi (Snakes)
Ni (Lion-Turtle, Ninken)
San (Bird)

Classification
Ninjutsu, Space–Time Ninjutsu

Rank
C-rank

Class
Offensive, Defensive, Supplementary