Paper is a thin sheet material that is usually manufactured from cellulose pulp derived from wood and other lignocellulosic materials such as cotton, rice, or wheat straw for writing, printing, and packaging purposes. Over the centuries, paper has been made from a wide variety of materials such as cotton, wheat straw, sugar cane waste, flax, bamboo, wood, linen rags, and hemp. Regardless of the source, fiber is needed to make paper. Today, fiber comes mainly from two sources: wood and recycled paper products.

The process of making paper involves two steps: extracting cellulose fibers from a variety of sources and converting them to pulp, and then combining the pulp with water and placing it on a paper-making machine where it is flattened, dried, and cut into sheets and rolls. The main sources of cellulose fiber are trees, which are the most common source of cellulose fiber (or wood pulp) . Besides wood pulp, paper can be made from other materials such as cotton, flax, esparto, straw, hemp, manilla, and jute.

Wood chips, which come from logs or from residues from sawmills, furniture manufacturers, and other sources, can be chemically or mechanically separated into individual wood fibers in a process called pulping. Pulp mills make pulp, a mixture of cellulose fibers and water used as the basis of all paper products. Recycled paper processing mills use paper as their feedstock. The recovered paper is combined with water in a large vessel called a pulper that acts like a blender to separate fibers in the paper sheets from each other.

In summary, paper can be made from a variety of materials, but the most common source of cellulose fiber is trees. The process of making paper involves extracting cellulose fibers and converting them to pulp, which is then combined with water and placed on a paper-making machine where it is flattened, dried, and cut into sheets and rolls.