What is pump over in red wine making?

Pump-Over: Also known as remontage, the process of pumping red wine up from the bottom of the tank and splashing it over the top of the fermenting must; the purpose is to submerge the skins so that carbon dioxide is pushed to the surface of the must and released. This kind of pump over wine fermentation tank have circulation pipe and Sprinkle which make sure the must can be well impregnated