In my story "magic" is both an energy and the name for the specific form ,unique to each user, that around 60% of the population can use, though this doesn't acount for the fact animals, items, and even locations can have magical abilites. Most magic comes from energy within the user called the Inner Fire, which is a limited but regenrating energy that can be used to preform ones own magic or can be used to send energy through magical pathways (magic itself can't interact with physical matter, think of it as punching a wall and breaking a bottle on the other side.) Magic strengthens the users body giving them faster reflexes, greater phyisical strength and speed, and sometimes other mutations (like blue skin or purple hair, or more extreme like having a body made completely of organic glass).
Magic users tend to get all their education out of the way by age 8, this is because they can process information much faster than a regular human (Though retention of said information is another thing, generally they forget as easily as any old joe). Besides the expected maths, liturature, and sciences, most schools will also teach some basic combat skills. At this stage the can opt to join the military, go into the work force, or get further education. The military, particularly that of the Empire has a further divide, training would generally end at arounnd 18, but one can go through the program faster, and one can attempt the Knight certification at any time, though it's a particularly grueling excercise consisting of rigorous physical and mental testing. Afterward one is further training to help them conform to the image of a knight
Magical abilites vary widely in what they do, one of the main characters has the ability to manipulate the extrinsic properties of anything including manipulating those properties relative to other properties (making line AB lead to point C somehow), another girl's magic ability makes her good at math (well it actually gathers numerical data, she does the math on her own). The most powerful magical abilites tend to be the most straight forward, and they also tend to have short range (though some of the most powerful abilites are powerful because they have universal or in one case multiversal range) There's also only one case of a single individual with two magical abilites, and both abilites are non-combat abilites.
There are also Mystery Gods in the settings, they also have Inner Fire based magic as well as magic based on an alternate realm called the Outer Inferno, a chaotic parralel dimension. called Mysteries. Most people can't survive in the Outer Inferno without special protection, but the Mystery Gods each have a realm within the Inferno called an Otherworld where they have extreme reality warping powers though they can't directly affect anyone with powerful magic resistance. They can also create pacts with anyone who will accept to create Daemons, the Keepers of Secrets. This is done by having a magic user drink the blood of a Mystery God they've sworn loyalty too. Unlike humans, Mystery Gods have an infinite amount of magic energy, and their are seperated into hierarchies based on how much power they can use at once (trying to use too much at once will just outright kill them). There is also one being much more powerful than any of the Mystery Gods by an ufatomable degree, and her power comes from different source than the Inner Fire or Outer Inferno and she can nullify any magic without effort.
Also of note is that magic is used generate electricity as well, and nearly everything uses mithril (which is an organic, and occassionally semi-sentient metalloid natrually found in crystals then pounded into a more metallic form through magical processes.)