Magic

Magic is a fundamental force of the universe, just like gravity. It is the force inherent in thoughts, ideas, emotions, and willpower - a force inherent to all thinking and feeling creatures. To manipulate it, however, takes a mind which can imagine something that doesn't yet exist: light where there was darkness, movement where there was stillness. It takes a mind which can tell a story about how the world should be which is so persuasive, the world believes it.
All humans are magic. This is just how the world works.

Manifestation

In the most basic sense, magic is a natural force, similar to gravity or electromagnetism, which comes from and responds to thought, emotion, and will. All living things generate this energy, which exists in a field similar to EM. Any creature intelligent enough to perceive the world and respond to its perception has a presence and an impact on the fabric of magic the way that mass has a presence and impact on the fabric of space-time. However, only beings who consciously perceive and interact with their own perceptions of the world can manipulate the world through manipulating their own impact on the fabric of magic. While there are several species smart enough to interact with magic, humans all over the world have taken this far beyond the basic applications of exaggerating their own strength, speed, or stamina.

Localization

Different cultures have different interactions with magic. The mountains, in particular, are home to clans of witches who pass down highly specialized knowledge of written magic -- manipulating human blood and bone into awe-inspiring magical arrays which can take years to design and weeks to build, but which perform consistently powerful magic which can survive the death of the creator.

Type

Metaphysical, Arcane