  Our knowledge of main-belt comets (MBCs), which exhibit comet-like activity
likely due to the sublimation of volatile ices, yet orbit in the main asteroid
belt, has increased greatly since the discovery of the first known MBC,
133P/Elst-Pizarro, in 1996, and their recognition as a new class of solar
system objects after the discovery of two more MBCs in 2005. I review work that
has been done over the last 10 years to improve our understanding of these
enigmatic objects, including the development of systematic discovery methods
and diagnostics for distinguishing MBCs from disrupted asteroids (which exhibit
comet-like activity due to physical disruptions such as impacts or rotational
destabilization). I also discuss efforts to understand the dynamical and
thermal properties of these objects.
