  We discuss the physics of vortices in the circumstellar disks associated with
young stellar objects. We elucidate the basic physical properties of these
localized storm systems. In particular, we consider point vortices, linear
vortices, the effects of self-gravity, magnetic fields, and nonlinear aspects
of the problem. We find that these vortices can exist in many different forms
in the disks of young stellar objects and may play a role in the formation of
binary companions and/or giant planets. Vortices may enhance giant planet
formation via gravitational instability by allowing dust grains (heavy
elements) to settle to the center on a short timescale; the gravitational
instability itself is also enhanced because the vortices also create a larger
local surface density in the disk. In addition, vortices can enhance energy
dissipation in disks and thereby affect disk accretion. Finally, we consider
the possibility that vortices of this type exist in molecular clouds and in the
disk of the galaxy itself. On all of these size scales, vortices can produce
long-lived structures which may correspond to observed structures in these
systems.
