  We review the empirical evidence for the validity of the Standard Electroweak
Theory in nature. The experimental data are interpreted in terms of an
effective Lagrangian for Z physics, allowing for potential sources of SU(2)
violation and containing the predictions of the Standard Electroweak Theory as
a special case. Particular emphasis is put on discriminating loop corrections
due to fermion-loop vector-boson propagator corrections on the one hand, from
corrections depending on the non-Abelian structure and the Higgs sector on the
other hand. Results from recently obtained fits of the Higgs-boson mass are
reported, yielding M_H < 550GeV [800GeV] at 95% C.L. based on the input of
swbar^2(LEP+SLD)=0.23165+-0.00024 [swbar^2(LEP)=0.23200 +-0.00027]. With
respect to LEP2, it is emphasized that first direct experimental evidence for
non-zero non-Abelian couplings among the vector bosons can be obtained even
with restricted e+e- luminosity.
