The omniverse is an infinitely large expansion of space, in which all of the different multiverses and universes coexist with each other. The different multiverses, universes, and dimensions are depicted in a similar fashion to cells in tissue, or a sort of deformed honeycomb; they are simply joined together in such a way that permits multiversal travel and leaves no empty space. If any empty space does end up coming into existence, it is instantly converted into an empty universe that can be shaped by anyone that has power that is greater than or equal to the Super Emeralds. The "middle" of the omniverse is where the multiversal government resides in the No Zone.
The currency of the entire omniverse is the Orbit, a blue sphere that is generally used for multiversal trade. However, this currency is not used by all universes, as some lack the required technology for multiversal travel.
Inhabitants of the Sonic the Hedgehog universes tend to call alternate universes Zones.