The term "cardboard" alludes to the fact that the image has been placed on a hard, thick piece of paper. This term has previously been used to describe a procedure in which images were pasted on cardboard and framed with glass fronts to preserve them. Today, "cardboard" means any thin sheet of paper. People have used different materials for printing purposes. Some of the most common materials include wood, cotton, hemp, linen, and rag. These materials are then processed using one of several methods to make them flexible enough to use as print media. The most common method is to beat out the fibers into soft sheets. This can be done by hand or with mechanical equipment. After the material is beaten out, it is soaked in water to make it more pliable. Then it is laid out to dry in an open area away from any source of heat or moisture. Drying can take several days depending on the size of the sheet and the type of fiber it is made of. When the sheet is completely dry, it is ready to use for printing. Printing processes were not always as advanced as they are today. In early times, people used simple tools to create drawings on paper. They would either draw directly on the surface of the sheet or use some kind of ink.