Paper is a flexible web or mat of pulp fibers of plant (usually wood) origin. It is widely used for printing, packaging, and sanitary applications and also has a wide variety of specialized uses. Paper is formed from a dilute aqueous slurry of pulp fibers, fillers, and additives. Fillers are inert materials such as calcium carbonate, clay, and titanium dioxide that make printing papers whiter and increase opacity (the ability to read print on one side of the paper without print on the other side of the paper showing through). Additives are materials used to improve the papermaking process and modify the final product. Additives include dyes, strength agents, and sizing agents (used to make paper resistant to water penetration).

Pulp is obtained by mechanical or chemical means or by a combination of the two. The two most common pulping methods are thermomechanical pulping and kraft chemical pulping...