The Core Worlds are considered to be the heart of the Dominion's power.
These worlds are the most advanced in the known universe, the area they are located in, creates a spherical shape.
Withing the center of this sphere lies Earth, it is considered the galactic center. Every map both in and outside the sphere use The Homeworld as a point of reference.
Even though there are some Seperatists who believe they should not do so.
All Core World systems have the capabilities for 2-way FTL-Travel via Mass Catapult.