The precise measurement of the fluctuations of the CMB will allow to
confirm the gravitational instability picture and then to measure with a
high precision level, without unambiguity, the various cosmological
parameters like the Hubble constant, the baryonic content of the
universe, its mean density, the cosmological constant, etc... This has
motivated several experiences as well as the decisions to have space
missions like MAP and Planck Surveyor. However, the present-day
observations does already allow to draw some conclusions. I will
present this analysis and discuss which kind of constraints can be set
with observations available by now.