Dry cleaning is a process of cleaning clothes and fabrics using a chemical solvent containing little or no water. It is typically used on clothes and fabrics that cannot withstand the rigors of a standard home washer and dryer. The dry cleaning solvent cleans the surface of materials but does not penetrate the fiber like water does in a washing machine. It also prevents stretching and shrinking. The dry cleaning process works by lifting stains and surface dirt away from the fabric using the solvent. The process involves immersing the clothes in a liquid solvent, agitating them gently, and then spinning them to remove the solvent. The solvent used in dry cleaning is typically tetrachloroethylene, also known as perchloroethylene or "perc," but alternative solvents such as trichloroethylene, petroleum spirit, and synthetic petroleum are also used. The dry cleaning process is beneficial for delicate fabrics and clothes that cannot be washed in a standard washing machine. The dry cleaning industry has evolved over time, and modern dry cleaning machines use a closed-loop system that results in high solvent recovery rates and reduced air pollution.