  We introduce integral identities to define delta-shock wave type solutions
for the multidimensional zero-pressure gas dynamics Using these integral
identities, the Rankine-Hugoniot conditions for delta-shocks are obtained. We
derive the balance laws describing mass, momentum, and energy transport from
the area outside the delta-shock wave front onto this front. These processes
are going on in such a way that the total mass, momentum, and energy are
conserved and at the same time mass and energy of the moving delta-shock wave
front are increasing quantities. In addition, the total kinetic energy
transfers into the total internal energy. The process of propagation of
delta-shock waves is also described. These results can be used in modeling of
mediums which can be treated as a {pressureless continuum} (dusty gases,
two-phase flows with solid particles or droplets, granular gases).
