Arcane magic is the direct manipulation of energy.
Arcane magic is created out of manipulation of the Weave. Anyone who can fully duplicate the gestures and sounds required of each spell can use arcane magic. Manipulating the Weave can be done via magical writings, Rune magic (though Rune magic is more involved with divine magic), Gem magic, Circle magic, etc.
Historically, arcane magic is the most unreliable form of magic.
The Arcane Focus