  We present AGNfitter: a Markov Chain Monte Carlo algorithm developed to fit
the spectral energy distributions (SEDs) of active galactic nuclei (AGN) with
different physical models of AGN components. This code is well suited to
determine in a robust way multiple parameters and their uncertainties, which
quantify the physical processes responsible for the panchromatic nature of
active galaxies and quasars. We describe the technicalities of the code and
test its capabilities in the context of X-ray selected obscured AGN using
multiwavelength data from the XMM-COSMOS survey.
