Methylene Diphenyl Diisocyanate, commonly known as MDI, is a chemical compound used primarily in the production of polyurethane foams. It is a type of isocyanate that reacts with polyols to create flexible and rigid foams, which are widely used in insulation, furniture, and automotive applications. MDI is known for its durability and resistance to heat and chemicals. It is typically produced in two forms: pure MDI and a mixture of MDI isomers. Safety precautions are essential when handling MDI, as it can be hazardous if inhaled or if it comes into contact with skin.