The Curse Mark is the juinjutsu that were one of the most frequently-used technique of Orochimaru, which he usually gave to his most powerful and unique followers. To apply a cursed mark, Orochimaru needed to bite his intended target. As he had sharp fangs and an extendible neck, this was a relatively simple task. The mark then appeared on the body of the victim near the point of application, and they subsequently lost consciousness. The design of the seals varied from person-to-person. Sometime later, had the victims survived, they would awaken with the first level of the seal active and be enraged due to the seal's influence. The seals worked by forcibly drawing chakra from the user's body, giving the user a chakra capacity beyond what they would normally be capable of, as well as increased physical performance, especially in battle.
The Curse Mark has two different levels, and the types of transformations differ from mark to mark. When inactive, the mark is simply a black tattoo on the user's body. Orochimaru has a wide array of cursed marks, so the appearance and power of the mark will usually vary from user to user. Each mark always has three identical marks arranged in a circular pattern. When first activated, the marks on the seal glow and replicate, spreading over the user's body. This is known as the first level (Jōtai Ichi; Literally meaning "State 1") of the mark. The degree to which this occurs is dependent on the user, and the degree to which it spreads is proportionate to the overall effect it has. Normally, the wearer of the mark will also experience slight pains during the activation of this level.
The second level (Jōtai Ni; Literally meaning "State 2") of the mark causes the black marks to completely envelop the user. This is followed by an unnatural alteration of the user's body, with the only common features being yellow eyes with a black sclera, skin changing color, and longer hair. When in this level, the mark eats away at the user's mind and personality, driving them to madness if used for too long. It also takes quite a toll on their body, since they are being mutated by the mark. Aside from the first and second levels of the mark, skilled users of the mark are able to perform partial transformations in which the aforementioned mutation caused to the user's body in the level two state can be used without altering the entire body. The power of the curse mark can even synchronize with the user's regular body with extended use, increasing the stats of their normal state for a short time.
Because the mark forcibly draw chakra from the user, they will often kill the user when first applied. Orochimaru has averaged a ten-percent success rate when applying these marks based on his first experiment with his ten students, with only one survivor. Additionally, even if the user survives, their body will not be able to easily control the power of the seals given to them. To compensate for this, Orochimaru developed the Awakening Pills. The drug forces the user's body to become accustomed to the unnatural increase in power, but also kills the one who takes it. The sealing technique Four Black Mists Formation and Dark Sealing Method are used to keep the drug from killing the user by placing them in a temporary death state. Prolonged usage of the seals would corrode both the body and mind, making it easier for the users to be susceptible to Orochimaru's influence.
Orochimaru originally developed the curse marks through experimentation on a boy named Jugo, whose body naturally produces an enzyme that triggers a state, on which the cursed mark is based on. The difference between Orochimaru's curse marks and the unrefined enzyme are the effect that they have: while the cursed seal is controllable, the unrefined enzyme, extracted from Jugo, produces uncontrollable rage and madness in those exposed to it, including Jūgo himself, and the effects cannot be controlled. Similarly, Jūgo is not limited to a single transformation, and can change the advantages of his form to fit the situation; while others would have their minds and bodies corroded by the seal, Jūgo is immune to such side-effects, due to being the main source of the enzymes. Also, anyone who survives the application of the Cursed Mark is "compatible" for Jūgo until his extraction from the curse mark.
It appears that the cursed seals are also partially made from Orochimaru's chakra. Kabuto stated that Anko Mitarashi was branded with one and contained some of Orochimaru's chakra inside her.
The Curse Mark tend to have fatal side effects if handled improperly, as seen when Mizuki's mark, which is unique in that it requires extra procedures to activate its powers, he nearly died due to using it earlier than he should, and lost all his powers regardless.