  Kuiper Belt Objects, or more generally Trans-Neptunian Objects (TNOs), are
planetesimals found beyond the orbit of Neptune. Some TNOs evolve onto
Neptune-crossing orbits and become Centaurs. Many Centaurs, in turn, reach
Jupiter-crossing orbits and become Jupiter-family comets (JFCs). TNOs are the
main source of the JFCs. TNOs offer a different window than the JFCs, of more
primordial bodies and over a different size and temperature range. It is in
that context that this chapter is written. Here we discuss the dynamical
pathways taken from the trans-Neptunian region to the JFCs, and the most
important properties of TNOs that relate to the JFC population, including
considerations of their origins, compositions, morphologies, and size
distributions. We relate these properties to the JFCs whenever possible. We
reflect on a few key outstanding issues regarding our incomplete knowledge of
TNOs as they pertain to the Centaurs and JFC populations. We finish with a
short discussion of notable new and upcoming facilities and the impacts they
will have regarding these outstanding questions.
