  Studying the properties of the W boson naturally plays a key role in
precision tests of the Standard Model. In this paper, the key measurements
performed at LEP and the Tevatron over the last decade are reviewed. The
current world knowledge of the W boson production and decay properties, gauge
couplings, and mass are presented, with an emphasis on the most recent results
from LEP2. Some estimates of the sensitivity of the upcoming Tevatron RunII are
also presented.
