The dust disks commonly observed around mature main sequence stars
(generally A to K2 type) are evidence that plantesimals are present in
these systems on spatial scales that are similar to that of the
asteroids and the Kuiper Belt obejects in the Solar system. It is
inferred that their dust mass declines with time as the dust-producing
planetesimals get depleted, and that this decline can be punctuated by
large spikes that might be due to individual collisional
events. Debris disks present a wide range of sizes and structural
features (inner cavities, warps, offsets, rings, clumps...) and there
is growing evidence that, in some cases, they might be the result of
the dynamical perturbations of a massive planet. Our Solar System also
harbors a debris disk and some of its properties resemble those of
extra-solar debris disks. Debris disks can shed light on the diversity
of planetary systems helping us place our Solar system into
context. This talk will review the debris disk phenomenon, the results
from Spitzer surveys and the modeling efforts.