  The Oort cloud and the scattered disk are the two primary reservoirs for
long-period and short-period comets, respectively. In this review, we assess
the known observational constraints on these reservoirs' properties and their
formation. In addition, we discuss how the early orbital evolution of the giant
planets generated the modern scattered disk from the early, massive
planetesimal disk and how $\sim$5\% of this material was captured into the Oort
cloud. We review how the Sun's birth environment and dynamical history within
the Milky Way alters the formation and modern structure of the Oort cloud.
Finally, we assess how the coming decade's anticipated observing campaigns may
provide new insights into the formation and properties of the Oort cloud and
scattered disk.
