  The angular power spectrum of the cosmic microwave background (CMB) contains
information on virtually all cosmological parameters of interest, including the
geometry of the Universe ($\Omega$), the baryon density, the Hubble constant
($h$), the cosmological constant ($\Lambda$), the number of light neutrinos,
the ionization history, and the amplitudes and spectral indices of the
primordial scalar and tensor perturbation spectra. We review the imprint of
each parameter on the CMB. Assuming only that the primordial perturbations were
adiabatic, we use a covariance-matrix approach to estimate the precision with
which these parameters can be determined by a CMB temperature map as a function
of the fraction of sky mapped, the level of pixel noise, and the angular
resolution. For example, with no prior information about any of the
cosmological parameters, a full-sky CMB map with $0.5^\circ$ angular resolution
and a noise level of 15 $\mu$K per pixel can determine $\Omega$, $h$, and
$\Lambda$ with standard errors of $\pm0.1$ or better, and provide
determinations of other parameters which are inaccessible with traditional
observations. Smaller beam sizes or prior information on some of the other
parameters from other observations improves the sensitivity. The dependence on
the the underlying cosmological model is discussed.
