  Observations of the Cosmic Microwave Background (CMB) temperature
fluctuations are a powerful tool for testing theories of the early Universe and
for measuring cosmological parameters. We present basics of CMB physics, review
some of the most recent results and discuss their implications for cosmology.
The Archeops balloon-borne experiment is designed to map the CMB with an
angular resolution of 10 arcminutes and a precision of 30 $\mu\mathrm{K}$ per
pixel. This will allow the measurement of the CMB fluctuation power spectrum
from large to small angular scales. We describe preliminary results from the
test flight which took place in July 1999 and present perspectives for upcoming
scientific flights (January 2001).
