  CMB anisotropy data could put powerful constraints on theories of the
evolution of our Universe. Using the observations of the large number of CMB
experiments, many studies have put constraints on cosmological parameters
assuming different frameworks. Assuming for example inflationary paradigm, one
can compute the confidence intervals on the different components of the energy
densities, or the age of the Universe, inferred by the current set of CMB
observations. The aim of this note is to present some of the available methods
to derive the cosmological parameters with their confidence intervals from the
CMB data, as well as some practical issues to investigate large number of
parameters.
