Colonization of the Universe
Human Civilization is believed to have begun in the Milky Way Galaxy some 20,000 years ago, with the colonization of the universe having begun when the first human colonies off of Old Earth were established on Mars in the 21st century C.E. The spread of human civilization was slow at first, limited to the solar system around Old Earth's host star, Sol. Colonies were established on various moons throughout the system, but it was not until the invention of the gravity drive in the 24th century that the human colonization of space began in earnest, when humans were able to venture to remote star systems to search for planets suitable for colonization.
The early era of space colonization, limited to the Milky Way Galaxy, involved searching for Earthlike planets around suitable host stars. Perfect candidates proved elusive, and the concessions humans had to make to establish colonies on remote planets spurred entire new fields of experimental engineering involving star and planet manipulation. Over the centuries, this led to the modern paradigm of human colonization involving starlifting procedures on red dwarf stars to increase their luminosity, and planetary encapsulation of ice and gas giant planets orbiting those stars to produce planets with conditions suitable for colonization. Encapsulating structures produce an artificial surface above a planet's atmosphere such that the surface gravity is set to be equal to that of Old Earth, or 9.81 m/s^2. As an example, Neptune, with a mass of 17.147 that of Old Earth, must have an artificial surface radius 4.14 times that of Old Earth to have the same effective surface gravity. Neptune's natural radius is 3.883 times that of Old Earth, meaning a structure would need to extend that radius by about .26 Earth radii, or about 1,650 miles above Neptune's present surface. This would create a usable planetary surface 215 times larger than that of old Earth.
The use of Neptune as an example is appropriate, as the typical colony is built atop an ice giant, and has between 200 and 300 times the surface area of Old Earth. The most populous colonies tend to top out at populations between 100 and 200 billion residents. A typical colonized system will also include outposts on moons and vast clouds of solar energy collectors orbiting beyond the inhabited planet's radius, as well as in the vicinity of the L3, L4, and L5 locations of its orbit. A handful of megacolonies, built atop larger planets with populations reaching as high as a trillion residents exist in some of the more populous galaxies, such as the Andromeda Galaxy and the King's Galaxy, though the practice of establishing colonies on very large planets fell out of favor some millennia ago, as the siting parameters are more restrictive, the construction is more expensive, and it has proven more efficient for prospectors to simply seek out alternative sites to establish cheaper, smaller colonies than to try to build enormous colonies.
It is estimated there are over 250,000 colonies spread throughout the Lanieakea Supercluster, with more in the Perseus-Pisces Supercluster. No colonies have been established in the Coma Supercluster, but several industrial sites and temporary habitats have. Temporary or small-scale habitats often include such things as domed lunar and planetary settlements as well as Bernal Spheres and other types of orbital space structures.
Prospecting
Intergalactic corporations, as well as small, independent prospectors, are continually scouring fringe galaxies and underpopulated galaxies for new host stars. Much of this can be done remotely via telescopic inspection, but, ultimately, on-site system scanning is required to verify a system's suitability. Should a Royal development grant be obtained, an architect is then dispatched to design and implement the establishment of a new colony, with naming rights going to the discoverer.