An inverter in relation to air conditioning terms is a type of air conditioning system that incorporates a power conversion circuit which provides optimum power control and extremely efficient operation by changing the frequency of the power supply to the compressor which varies the cooling heating capacity, so even though you get accurate, smooth and flexible operation, you use less electricity than conventional units.
Please note that energy savings are only realized when the system is correctly sized. Undersized inverter systems will cost more to run than a correctly sized system. Inverter systems run much more efficiently at 30 to 70% of their full capacity.