  We present an analysis of the Suzaku observations of the prototype wind-blown
bubble NGC 6888 which is based both on use of standard spectral models and on a
direct comparison of theoretical models with observations. The X-ray spectra of
NGC 6888 are soft and most of the X-rays are in the (0.3 - 1.5 keV) energy
range. But, hard X-rays (1.5 - 4.0 keV) are also detected (~10% of the observed
flux). The corresponding spectral fits require a relatively cool plasma with kT
< 0.5 keV but much hotter plasma with temperature kT > 2.0 keV is needed to
match the observed hard X-ray emission. We find no appreciable temperature
variations within the hot bubble in NGC 6888. The derived abundances (N, O, Ne)
are consistent with those of the optical nebula. This indicates a common origin
of the X-ray emitting gas and the outer cold shell: most of the X-ray plasma
(having non-uniform spatial distribution: clumps) has flown into the hot bubble
from the optical nebula. If the electron thermal conduction is efficient, this
can naturally explain the relatively low plasma temperature of most of the
X-ray emitting plasma. Alternatively, the hot bubble in NGC 6888 will be
adiabatic and the cold clumps are heated up to X-ray temperatures likely by
energy exchange between the heavy particles (hot ions diffusing into the cold
clumps).
