Basic Terminology

Maestro – A regular human who can grant their own spiritual energy, known as Rhythm to Demi-humans known as Resonators to allow them to perform magic.
Resonator – A Demi-human contracted to a Maestro through a device called a Tuner. They can turn a Maestro's Rhythm into spells, almost like a filter for a Maestro. Their own Rhythm is primarily used defensively, like body armor.
Tuner – A device which controls the flow of Rhythm between a Maestro and Resonator. The Tuner is bound to the Resonator by the way of a neural implant. The traditional school of thought is handing over a Tuner to another Maestro is the same as handing the Resonator to that Maestro.
Rhythm – A magical energy contained within the bodies of all living things
Tacet - Those who have not awakened their rhythm simply from not knowing it exists
Melopomorph - The three bipedal rhythm-using races of Riterra (Maestros, Resonators, Naturals). Human is sometimes used as an umbrella term for Maestros and Resonators (typically leaning more towards Maestros), while Naturals are always referred to as Naturals even amongst different species.

Resonators have two main classifications, Element and Attribute. For information on how Element and Attribute affect resonators outside of their basic elemental and spell affinities please see this page