  I review results from {\sl Chandra} observations of nearby normal edge-on
galaxies (Sd to Sa types). These galaxies have a broad range of star formation
rate, but none of them is dominated by a nuclear starburst. The galaxies are
all in directions of low Galactic foreground absorption. Extra-Planar diffuse
soft X-ray emission is detected unambiguously from all the galaxies, except for
N4244 (Sd), which is low in both the stellar mass and the star formation rate.
The thermal nature of the X-ray-emitting gas is well established, although its
chemical and ionization states remain largely uncertain. The X-ray luminosity
of the gas is proportional to the star formation rate and to the stellar mass
of the galaxies. But the luminosity accounts for at most a few percent of the
expected supernova mechanical energy input. Therefore, there is a ``missing''
energy problem for spiral galaxies. Much of the energy in late-type spirals may
be converted and radiated in lower energy bands. But early-type ones most
likely have outflows, which are powered primarily by Type Ia supernovae in
galactic bulges. These galactic outflows may strongly affect both the dynamics
and cooling of the intergalactic gas accretion, hence the evolution of the
galaxies.
