  The Pluto system is an archetype for the multitude of icy dwarf planets and
accompanying satellite systems that populate the vast volume of the solar
system beyond Neptune. New Horizons' exploration of Pluto and its five moons
gave us a glimpse into the range of properties that their kin may host.
Furthermore, the surfaces of Pluto and Charon record eons of bombardment by
small trans-Neptunian objects, and by treating them as witness plates we can
infer a few key properties of the trans-Neptunian population at sizes far below
current direct-detection limits. This chapter summarizes what we have learned
from the Pluto system about the origins and properties of the trans-Neptunian
populations, the processes that have acted upon those members over the age of
the solar system, and the processes likely to remain active today. Included in
this summary is an inference of the properties of the size distribution of
small trans-Neptunian objects and estimates on the fraction of binary systems
present at small sizes. Further, this chapter compares the extant properties of
the satellites of trans-Neptunian dwarf planets and their implications for the
processes of satellite formation and the early evolution of planetesimals in
the outer solar system. Finally, this chapter concludes with a discussion of
near-term theoretical, observational, and laboratory efforts that can further
ground our understanding of the Pluto system and how its properties can guide
future exploration of trans-Neptunian space.
