Presentation #201.04 in the session Stars, Cool Dwarfs, Brown Dwarfs I.
It is clear that massive gas objects strongly affect the architecture of planetary systems; hence, understanding their formation and evolution is extremely important. These objects, called substellar objects, are not massive enough to sustain hydrogen fusion as stars do and are composed of brown dwarfs and extrasolar giant planets. As these two groups have many similar properties, the best way to characterize and distinguish them is intensively debated. The current definition is based on the mass, as electron degeneracy pressure in the interior of BDs causes them to have a similar radius as giant planets. However, using the more fundamental formation process can better distinguish these two groups of objects. Objects formed via core accretion in a protoplanetary disk would be extrasolar giant planets, and those via gravitational instability would be brown dwarfs. Transiting substellar objects are especially suitable for studying their formation and evolution history using studies of their interior, tidal interactions, orbital parameters and atmospheres. I will present the current sample of known transiting substellar objects and highlight some exciting systems.