Magic is an ability some beings have to alter, sense, and control the world around them with spells or other efforts of spirit and will.
Some examples include:
Elrond seeing far off things as though he was right there.
Galadriel enabling her horse to run much faster than normal.
The Stranger's powers of temperature control, healing, blasting air, and commanding fireflies.
The Orc Sigil Hilt magically reforges itself when fed blood by its user.
In myth, an elf warrior who poured light into a tree to save it, while a Balrog infected it with his hate and flames.[1]
Magic can be dangerous, such as when the Stranger bruised his hand using a wind repulse against some wargs.[1]