Magic

Magic (魔術) is a term used to refer to supernatural phenomena that cannot be explained or analyzed via any sort of scientific means and reasonings. In the Toaru Majutsu no Index universe, magic is a complex system of arts, disciplines, and traditions that are firmly grounded in laws and knowledge that are wholly unknown and beyond the grasp of human sciences, which sought to manipulate and distort certain aspects of reality.

Also called the occult, conflicts with the magic side, the secret underworld that deals with magic and the occult, are the primary and most recurring plot points of the series.

History
Magic by itself roots from the simple fact that 'those without talent' wanted to be able to do the same things as 'those with talent' - namely Esper and Gemstones.

Styles
Many of the magic spells etc. is based on a certain set of laws - e.g. Celtic or Norse. But there are no strict division, because one base can be based on another base - e.g. Norse mythology was influenced by Celtic culture. However, magic users often use magic that is inherently part of their culture, like Kaori using her Amakusa spells based from Shinto, Buddhist, and Christian origins.

In the end, religion plays a key role in magic, as cultures and traditions of a certain population are tied to it. For example, Agnese Sanctis once belived that all magic that does not stem from Roman Catholicism is black magic.

Western magic
As the West is dominated by Christianity, most magic users are influenced by it one way or another, alongside whatever cultural traditions they've grown up with. This also includes pagan or pre-Christian origins, for example the Roman Catholics, despite their stringent adherence to the use of their own magical traditions, used Wooden Stake magic, the origins of which came from the Pythagoran Order. As well as the magic names used by English magicians used Latin

Organizations
Magic is used to realize a certain goal. So all magicians wield their power for themselves to realize this goal. These goals are carved into themselves in Latin - Magic Names. Magicians often use an organization like magic cabals or denominations to realize their goal.{[cite}}