3M is a diversified science-based group of multinational companies based in the United States. It was founded in 1902 with the aim of exploiting mineral deposits for grinding-wheel abrasives, initially concentrating on sandpaper and inventing a water-proof sandpaper in the 1920s. They began expanding into other products, inventin masking tape in 1925, and later moving into video tape, microfilm, printing plates, post-it notes, print cartridges, pharmaceuticals and fabric cleaning products.