Magic, in the Inheritance Trilogy, is an integral part of the world in which the story takes place. Magic is a force that exists in nature, like gravity. Those born with an innate talent are able to "reach for" this magic by different means.In the lifetime of Eragon Shadeslayer, practice had fallen into disrepair. The Master Oromis, an Elven Elder, was one of the last beings in Alagaesia to hold a true learning of it.

Humans, Elves, or any other living things are not the source of magic (or gramarye in the ancient language). Magic that is wild is often much more powerful than any living creature.

Magicians, before the creation of the Ancient Language, merely had to be born with that innate ability, and then had to think in their own languages. To use the magic in those days energy was required in only small amounts, as it is energy that generates magical power. Magic leaves its user fatigued. If you use magic, it will take the same amount of energy required to perform the task physically.
Attributes such as the distance from the target and the severity of the magic affect the amount of fatigue the user gains. Extremely powerful magic will overcome the user, draining the caster of vital energy until the caster either dies or the spell is completed. A magic-user also cannot raise anyone or anything from the dead, because an abyss exists between life and death where magic means nothing. If a magic-user tries to raise someone from the dead, they will lose all of their energy and die instead. A user of magic does not have the ability to stop a spell after they have begun it unless and until the task is completed or the task uses up all of their energy, in which case, again, they'll be left dead and their task unfulfilled.
Spells should be used in a sequence so if you know you are about to die from your own spell, you can break off the spell and save yourself. The method of thinking the spell in the spell-weaver's own language method was extremely dangerous, as stray thoughts could enter the mind and end up releasing great evils upon the land. An event that nearly destroyed every living thing on the earth brought out the Grey Folk.
They are the ancient race of Elves before they were altered by their bond with the Dragons but most of their history is unknown, except it was known they possessed powerful magic. The Grey Folk, realizing what could happen if such an event were to happen again, gathered their strength and wrought the greatest, most powerful spell ever performed with success. The Grey Folk used all their energy casting the spell, and almost all the spell-weavers died. But they actually changed the nature of magic itself using the spell. First of all, you must still be born with that innate ability of magic so you can access it. Secondly, they made it so that their language, the ancient language, controlled what the magic would do. For example, if you said burn the door, and looked at someone and thought of that person, the door would still burn. However, it is still possible to think the word in the ancient language, giving you the advantage of surprise. If you know the name of a thing in the ancient language, you will have complete control over it. This also includes a person’s real name in the ancient language, which is hidden from most. The ancient language has two unique traits; one, it describes the true nature of things, and two is that it is impossible to lie when speaking in this language. In Alagaësia, the language is spoken by the elves, which are not really the creators of this language but rediscovered it and taught it to the rest of the world. Apparently, everything once spoken in this language after the time the nature of magic changed, but no more. Magic is also accessed by wizards and witches through spells and potions. Sorcerers have an inborn talent as well, but it is different than Riders, as sorcerers and Shades summon spirits to perform magical acts, but can be possessed by spirits they summon. If this happens, they become a Shade - an innately evil creature that can only be killed with a blow through the heart. Dragon Riders gain powerful magic through forging a bond with their Dragon and through the Dragon, a bond with the primal forces of the land. Some of the basic magical techniques taught to spell weavers are these: The ability to extend your consciousness beyond you and meld your consciousness with other living things consciousnesses. They learn how to attack a persons mind and gain control over that person, and are taught to close their mind to the ones assaulting them by thinking of one thing only. They were taught how to place wards around themselves to help defend against both magic and physical assaults. These wards only survive as long as the warder can maintain them using the energy in their bodies. In magical battles, the opponents do not attack until they have broken into the mind of their enemy for two reasons; the fist being that in the instant before the magic takes place, the enemy has a chance to retaliate, and second is that is they are in the enemies mind they can now sense whatever attack they will throw at them. Most magical duels last for only a few seconds before both sides is destroyed, although those who are more disciplined have longer battles. In battles between armies, a spell weaver will only have an army to make sure they are protected while they are involved in their mental struggles. In order to defend their troops against the attacks of enemy magicians, they spread their own spell weavers out into different parts of the army and are responsible for putting wards around their charges. Magicians seeking to break these wards must batter past the mind of the spell weaver maintaining the wards and take control. Spell weavers also spread their minds outwards in order to sense enemy magicians. Some of the secrets of magic, preserved for only the wisest and most experienced Riders are listed below. An ability that only experienced Riders learn were twelve death words that can kill an entire army by cutting off certain nerves or arteries and only using as much energy as you would to lift a finger. They also learned how to meld matter and energy together to give that matter certain attributes not natural to it or to be released later. They were also taught the spell that could instantaneously transport an item or thing. They learned spells to identify poisons in food and drinks and how to perform an alternate version of scrying that allows the Rider to hear as well as see. Finally, one of the most potentially dangerous techniques; the ability to draw energy from your surroundings, including the earth and living things of all kind. One secret yet to be revealed is how Galbatorix's strength continues to increase each year.