Esper

An Esper (能力者) is a term used to refer to a person who emits AIM. It is also a term used to describe any individual who has gone through the Academy City Power Curriculum Program and magicians who are unaware they have magical powers and end up having to equate their powers as esper abilities.

Terminology
The original Japanese light novels used the term "Ability User", but before the licensing of Toaru Kagaku no Railgun, the majority of the English-speaking fandom substituted it with "esper". Because its use has become widespread, this wiki uses the term "esper".

A queer event related to this is Seven Seas' English translation of the first volume of A Certain Scientific Railgun, which opted to use "psychic", a term that has been used before by the fandom until "esper" became the standard. Because of this, the English fans that were accustomed to the use of "esper" lobbied for "psychic" to be changed, and Seven Seas acquiesced, even referencing the incident later.

The term "esper" does not automatically imply ESP, one of the two classifications of powers in Academy City, as it could also refer to an ability user that does not have extrasensory perception but instead influences objects in their surroundings, referred to as Psychokinesis. Abilities such as Pyrokinesis are considered esper powers despite the user not having extrasensory perception.

Characteristics
Index refers to espers as beings who have talent—most likely referring to Gemstones and as such are unable to use magic without causing much harm to one's body. All espers emit AIM, which is unique to the esper's powers, for example: a pyrokinetic esper will heat up their surroundings unconsciously more than any other person due to their AIM. Furthermore, all espers have what is called a Personal Reality, which is the basis of an esper's power and refers to the espers' ability to replace ordinary reality with his/her own. It is in contrast with magic's Idol Theory.

Regarding abilities, all espers can only have one type of esper power, for example: Misaka Mikoto is an Electromaster and is in control of all electrical phenomena. Although, this did not stop researchers from finding ways to achieve more than power such as Dual Skill and Multi-Skill. In contrast however, esper powers need no such preparation and elaborate rituals to create some sort of phenomenon or effect in reality.

Moreover, esper abilities are categorized as either Active or Passive abilities. Active refers to an esper knowingly having to use his power to create an effect on reality, whilst passive has the esper subconsciously effect reality with their abilities. However, both can be present at the same time in an esper, such as Accelerator's subconscious reflection ability.

Their distortion of reality to create powers is based on quantum theories. This distortion is an isolated phenomenon, pertaining only to the observations of the world by an esper based upon their Personal Reality. This is in stark contrast with holism, where a large distortion of the laws of the world as a whole is used to create powers.

Power Curriculum Program
All those who enroll into the program are referred to as espers. The purpose of the program is to cut an esper from regular reality. Through the use of experiments, drugs and the like, a student can get cut-off from regular reality and achieve their own personal reality. They are later given ranks depending on the results they have in a System Scan. It has been stated that even those who have a Level 0 rank have enough esper ability to barely pass grading on the esper curriculum.

All espers are theoretically able to gain an ability or gain a level using the curriculum, such as Misaka Mikoto, a Level 1 at first becoming the 3rd Level 5. Of course, there are exceptions such as the existence of Level 0s. Furthermore, with the Parameter List, it is apparent that there are certain limits that humans wanting to become espers using the curriculum have, such as some having a slower development compared to the rest. As such, Academy City allocates their resources and money for the helping of students who would become an esper faster.

All those who are part of the Power Curriculum Program will be listed within the Data Banks of the city, along with their power, level, as well as some comments regarding the person. Furthermore, certain espers such as Kamijou Touma have certain security protocols to protect the truth regarding their powers.

According to Uiharu Kazari, esper ability names are decided on by the school, like simple ones such as Electromaster or Telekinesis. However, there are also esper abilities that are decided by the student like Railgun. It is unknown what criterias are required to have one name their own esper ability, though uniqueness of the ability may be a factor.

Currently, only Academy City is able to produce Espers; although others have tried, such as the Stargate Project.

Gemstones and speculation
A Gemstone is a type of esper that has not gone through any power development program, but is still able to emit AIM. They are most likely the beings that Index referred to as "talented", and the reason that ordinary beings created magic to compensate for their lack of powers. There are currently 50 confirmed Gemstones in the world.

In extension to this, it has been speculated that there may be people who have not realized that they have powers, or that their certain propensities or idiosyncrasies, as subtle as good looks or good penmanship, may actually have this power.