Esper

An Esper (能力者) is an individual who emits AIM. The term is also used to refer to those who have enrolled in the Academy City Power Curriculum Program and magicians ​​​​​who are unaware of the nature of their magical abilities and thus result to describing them as esper-related.

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
Espers are describe by Index to be individuals with "talent"; this most likely refers to Gemstone espers and each is unable to practice magic without inflicting injury to their respective bodies. AIM is emitted by every esper; its properties are unique and depend on its emitter and their respective powers. For example: the AIM emitted by a Pyrokinetic esper will act to heat up their surrounding environment. Furthermore, espers have a Personal Reality; it is the basis of their esper abilities and is their capacity to substitute standard reality with their own. It is in contrast to the Idol Theory of magic.

Espers are allowed only one specific esper power; Misaka Mikoto for example is an electromaster esper in control of phenomena associated with electromagnetism.[​5]​ ​ Despite this however, researchers have made attempts to identify methods for producing espers with multiple powers, such as either Dual-Skill or Multi-Skill espers. Aside from their required mental performance of calculations, espers require zero elaborative and preparatory rituals to produce effects in relation to their abilities.

Moreover, esper abilities are compartmentalised into two categories: Active and Passive categories. Applications of active abilities require conscious, voluntary effort; applications of passive abilities require subconscious, involuntary effort. Esper abilities can be classified as both active and passive, such as Accelerator's reflection ability.[​6]​ ​

Their interference with and subsequent distortion of reality to produce detectable esper-related effects is based on quantum theory. Their interference and distortion are isolated phenomena, 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 interference with and thus distortion of the laws of the world as a whole are used to produce effects in relation to their abilities.[​7]​ ​

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.