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 contractors own blood. 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. It should be noted that anyone can summon the animal as long as they have the blood from someone who has made a contract, along with sufficient chakra of their own. 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.
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.
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.
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 defenses. Items can also be "summoned" from scrolls and also through a yet unnamed means which does not involve seals or blood. 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.