  The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in
five frequency bands between 23 and 94 GHz. The primary goal of the mission is
to produce high-fidelity, all-sky, polarization-sensitive maps that can be used
to study the cosmic microwave background. Systematic errors in the maps are
constrained to new levels: using all-sky data, aspects of the anisotropy may
confidently be probed to sub-microKelvin levels. We give a brief description of
the instrument and an overview of the first results from an analysis of maps
made with one year of data. The highlights are (1) the flat Lambda-CDM model
fits the data remarkably well, whereas an Einstein-de Sitter model does not;
(2) we see evidence of the birth of the first generation of stars at z ~ 20;
(3) when the WMAP data are combined and compared with other cosmological
probes, a cosmic consistency emerges: multiple different lines of inquiry lead
to the same results.
