The name is a bit misleading. The dry cleaning process isn't actually dry at all, it simply means that water isn't used in the process. At a commercial dry cleaners they use washing machines that are filled with a solvent to clean the garments, but no water. The reason it's necessary to do this is that some fabrics, like silk, rayon and wool blends, don't react well to the hot water in a domestic washing machine and can stretch and become misshapen. The strength of the solvent used also means it can often tackle stains that normal washing can't shift.