  The phenomena of the microwave induced zero resistance states (MIZRS) and the
microwave induced resistance oscillations (MIRO) were discovered in the
ultraclean two-dimensional electron systems in 2001 -- 2003 and have attracted
great interest of researchers. In spite of numerous theoretical efforts the
true origin of these effects remains unknown so far. We show that the MIRO/ZRS
phenomena are naturally explained by the influence of the ponderomotive forces
which arise in the near-contact regions of the two-dimensional electron gas
under the action of microwaves. The proposed analytical theory is in agreement
with all experimental facts accumulated so far and provides a simple and
self-evident explanation of the microwave frequency, polarization, magnetic
field, mobility, power and temperature dependencies of the observed effects.
