The world of ד-Earth (Dalet-Earth) is nearly identical to א-Earth. However, the main discerning difference is going to be that of an ancient (possibly alien, or at least non-human) civilization, which developed advanced transportation systems across the galaxy. This transportation network, however, has long since been abandoned and forgotten. What exactly happened to this ancient civilization is as of yet a mystery. One possibility is that it still exists elsewhere, and it was simply this section of the transportation network which has been abandoned.
This network is composed of a few different methods of transportation. All of these methods are based around a series of waypoints waypoint stations. These waypoints serve to coordinate destination points for teleportation. Larger, space station sized waystations lack the resolution in their tracking to coordinate precise enough locations for teleporting onto a planet's surface, so smaller waypoints on the planet's surface are required for direct teleportation to the planet's surface. These smaller waypoints, however, also have a shorter range, meaning a lot of them are required to cover the entire planet's surface. These space-station sized waypoints, often housed, in addition to the way-points themselves, meeting places, markets and more. They acted as central hubs for local commerce.
In addition to teleportation, aided by these waypoints, semi-permanent links between two locations were also able to be established. These function as portals. Portals between base stations on planets surfaces are able to connect to bays of these such portals on the space stations. This allowed for easy and sustained access to these central hubs. Teleportation, on the other hand, was mostly used by ships. Personal teleporters, for most people, were either too expensive, rare, or otherwise impractical for the majority of people.
Each of these waystations additionally has one larger portal, which is capable of connecting to other waystations in the local area, while the smaller portals are only capable fo connecting to the portals of the surfaces of planets within it's range. Within the local area, there is one even larger waystation, capable of connecting to other larger waystations outside of the local area, each with their own network of smaller stations.
Additionally, an older version of the technology still exists in some locations, which involved teleportation chambers, which utilize teleportation without the addition of navigation to an arbitrary point.
The waypoints, stations and portals on Earth were buried and forgotten long ago. Some people possibly know of their existence, having been rediscovered in modern times. Although the system of dialling different portals or teleportation coordinate is somewhat complex, and difficult to brute force. Meaning that even those who know about these locations do not necessarily have free movement between all of the different portals, waypoints and waystations.