Milky Way
One of many casual names for a barred spiral galaxy (type SBbc) comprised of an estimated two hundred to three hundred billion stars: one of the two largest / most massive members of the so-called Local Group of thirty-five galaxies. The galaxy is approximately 110,000 light years in diameter and approximately 12,000 light years thick (except at its core, where the thickness is more like 30,000 light years). It is gravitationally associated with thirteen satellite galaxies, mostly dwarfs or irregulars, which are also members of the Local Group; and it also has a halo of globular star clusters which oscillate in and out of the main Galactic body over long periods of time.
The Milky Way is the home galaxy of the planet Earth, the solar system of which lies out at the edge of a large arm called the Orion Arm, itself a branch of the neighboring Sagittarius Arm.
Wizardly management structure takes the physical structure of the Galaxy into consideration for administrative purposes. Each arm of the Milky Way has an Arm or Galactic Regional Supervisor responsible for the general supervision of wizards and the conduct of wizardry in the region, especially as it pertains to relationships between empires or similar associations of inhabited worlds. (Some regions have a second or separate Regional Supervisor who specializes in handling "independent" worlds such as Earth -- planets not members of larger administrative areas, or otherwise non-affiliated due to insufficient technological expertise, adverse xenognomic response, or sevarfrith status.) There is also a Galactic Coordinator to whom the Regional Supervisors report. Wizards promoted into this position normally come from the longest-lived species native to the Galaxy, as species with median lifespans of less than ten thousand (Earth) years normally have difficulty amassing and getting sufficiently to grips with the information and history of the Arm-Regions to administer them effectively.