  We compare the latest observations of Cosmic Microwave Background (CMB)
Anisotropies with the theoretical predictions of the standard scenario of
structure formation. Assuming a primordial power spectrum of adiabatic
perturbations we found that the total energy density is constrained to be
$\Omega_{tot}=1.03\pm0.06$ while the energy density in baryon and Cold Dark
Matter (CDM) are $\Omega_bh^2=0.021\pm0.003$ and $\Omega_{cdm}h^2=0.12\pm0.02$,
(all at 68% C.L.) respectively. The primordial spectrum is consistent with
scale invariance, ($n_s=0.97\pm0.04$) and the age of the universe is
$t_0=14.6\pm0.9$ Gyrs. Adding informations from Large Scale Structure and
Supernovae, we found a strong evidence for a cosmological constant
$\Omega_{\Lambda}=0.70_{-0.05}^{+0.07}$ and a value of the Hubble parameter
$h=0.69\pm0.07$. Restricting this combined analysis to flat universes, we put
constraints on possible 'extensions' of the standard scenario. A gravity waves
contribution to the quadrupole anisotropy is limited to be $r \le 0.42$ (95%
c.l.). A constant equation of state for the dark energy component is bound to
be $w_Q \le -0.74$ (95% c.l.). We constrain the effective relativistic degrees
of freedom $N_\nu \leq 6.2$ and the neutrino chemical potential $-0.01 \leq
\xi_e \leq 0.18$ and $|\xi_{\mu,\tau}|\leq 2.3$ (massless neutrinos).
