Hand Seal

are used to perform many ninjutsu, genjutsu, and other secret arts other than taijutsu. The exact amount of chakra necessary to perform a jutsu is manipulated through hand seals. There are different sequences of hand seals for every technique, requiring memorization.

While techniques may require a number of hand seals to work, a skilled ninja can use less or even one to perform the same technique. An example of this is the Water Release: Water Dragon Bullet Technique, which requires a total of 44 hand seals to activate. Tobirama Senju, the Second Hokage, however, just needed to use one hand seal to complete the technique, a testament to his skill. In fact, by Part II, Sasuke Uchiha has managed to master the Chidori to the point of not needing a single hand seal to invoke it.

Although rare, it is possible for a shinobi to be able to do hand seals with just one hand. The only shinobi so far capable of this are Haku and Guren.

Basic Seals
There are twelve basic seals, each one named after an animal of the Chinese zodiac.

Other Hand seals
Besides the twelve basic hand seals, there are unique hand seals used for certain techniques. These hand seals are rarely seen, and can be considered unique to specific jutsu.

Tiger/Ram with one hand
Although it's unknown if this is a seal, this motion is often used to concentrate chakra, and many shinobi are seen initiating simple, basic jutsu after making this seal. Deidara also often used this when he detonated his Exploding Clay.

Clap hands
This seal is a special seal that is used in several techniques. To perform this hand seal, the user simply claps their hands together. The hand seal sequence for powerful summoning Kinjutsu like the Summoning: Impure World Resurrection and the Dead Demon Consuming Seal end with this seal; similarly, Jiraiya prepares to enter Sage Mode (summoning Shima and Fukasaku) by performing this hand seal and sustaining it. Once the seal sequence completed, the user's hands are held in this position until the desired effect is achieved.

Slam ground
Used in techniques such as the Summoning Technique, this is more of an initiation of a jutsu than a seal. The user slams the surface that is affected.

Half Tiger
No official name, it resembles the Tiger seal, but only the index fingers are raised. It is used in many different jutsu.

Jin Seal
This is another one of the seals that are used in normal techniques, yet isn't one of the basic twelve seals. The seal is used in techniques such as the Water Release: Water Dragon Bullet Technique and the Shrine Seal. It is unknown how this seal is formed.

Unknown Common Seal
The Akimichi clan use a certain seal in their Multi-Size Technique, which also resembles the Bird seal from frontal view. (However, it is confirmed that this is a different seal, as the Bird seal has been seen in a side view in techniques such as Water Release: Water Dragon Bullet Technique and the Shadow Sewing Technique.) The index and little fingers are raised up, while the middle and ring fingers are folded down and interlocked. Sasuke also used this seal, or a very similar seal, in his battle with Deidara, when he used either Hidden Shadow Snake Hands or Snake Authority Spell.
 * This seal is very controversial, as this seal was used instead of the Bird seal multiple times in the anime or in movies, likely a mistake.

Shadow Clone Seal
The Shadow Clone Technique seal is different from the basic twelve seals. Index and middle fingers from both hands are crossed.

Haku's Seals
The seals used for Haku's Thousand Flying Water Needles of Death, are quite different than the basic twelve seals, and are also performed with one hand.

The Demonic Ice Crystal Mirrors jutsu can be done with a special seal, which resembles Tiger with middle fingers crossed over the index fingers. Interestingly, Orochimaru also uses this seal when giving the Cursed Seal of Heaven to an individual.

Mind Technique Seals
The Yamanaka clan uses different seals to activate their techniques, such as the Mind Body Switch Technique and the Mind Body Disturbance Technique. Another seal was used to release the Mind Body Switch Technique and return to the original body. This seal resembled both hands' fingers straightened and crossed into an "X", similar to the Ox seal, but without the left middle and ring fingers down.

Tornado Lightning Seal
In Naruto the Movie 2: Legend of the Stone of Gelel, Ranke uses an unknown hand seal to activate her Tornado Lightning.

Shrine Seal
The Shrine Seal used by Shion (and a variation used by Yomi) uses a numerous amount of different seals with different names as followed:

Hatsu → Jin → Kai → Min → Shin → Gan → Reppyo → Shōzen → Mika → Dan → Raku → Shō → Fu → Sai → Dan → Gika → Ragu → Bagi

Hiruko's Storm Release Seal
In Naruto Shippūden 3: Inheritors of the Will of Fire, Hiruko uses a special seal for the Storm Release: Thunder Cloud Inner Wave, which resembles Tiger, but only with the middle fingers raised.

Fūma Curse Mandala Seals
The Fūma Clan used various unknown hand seals for their Hiden jutsu, the Curse Mandala.

Twin Snakes Mutual Death Seal
A hand seal involving both the user and the enemy is used in the kinjutsu Twin Snakes Mutual Death.

Daytime Tiger Seal
This seal is used in Daytime Tiger. It does not release chakra, but rather keeps it inside the body to use as energy and strength. This creates a missile type of jutsu which is not a body of chakra. This seal is actually based off one of the original Kuji-jin seals, the seal of the Outer Lion. In this case, the hands are meant to resemble a tiger. The index fingers (the "eyes" of the Tiger) glow green with the evaporating green sweat of the user (result of releasing the Gate of Wonder).

Guren's Unknown Crystal Seals
Several "unknown" seals are used in Crystal Release: Crystal Encampment Wall.

Anime Byakugan seals
In the anime, certain variant seals to aid in the activation of the Byakugan are seen. Most are some of the basic twelve seals, but several are different.

Anime Water Encampment Wall
In the anime, a special seal is used instead of what is seen in the manga for the Water Release: Water Encampment Wall Technique.