  Planetary nebulae (PNe) are an exciting addition to the zoo of X-ray sources.
Recent Chandra and XMM-Newton observations have detected diffuse X-ray emission
from shocked fast winds in PN interiors as well as bow-shocks of fast
collimated outflows impinging on the nebular envelope. Point X-ray sources
associated with PN central stars are also detected, with the soft X-ray (<0.5
keV) emission originating from the photospheres of stars hotter than ~100,000
K, and the hard X-ray (>>0.5 keV) emission from instability shocks in the fast
stellar wind itself or from a low-mass companion's coronal activity. X-ray
observations of PNe offer a unique opportunity to directly examine the dynamic
effects of fast stellar winds and collimated outflows, and help us understand
the formation and evolution of PNe.
