  This review addresses the state of research that employs astronomical (remote
sensing) observations of solids ("dust") in young circumstellar disks to learn
about planet formation. The intention is for it to serve as an accessible,
introductory, pedagogical resource for junior scientists interested in the
subject. After some historical background and a basic observational primer, the
focus is shifted to the three fundamental topics that broadly define the field:
(1) demographics -- the relationships between disk properties and the
characteristics of their environments and hosts; (2) structure -- the spatial
distribution of disk material and its associated physical conditions and
composition; and (3) evolution -- the signposts of key changes in disk
properties, including the growth and migration of solids and the impact of
dynamical interactions with young planetary systems. Based on the state of the
art results in these areas, suggestions are made for potentially fruitful lines
of work in the near future.
