A Hollander beater is a machine invented by the Dutch in 1680 to create paper pulp from plant fibers containing cellulose. The Hollander chopped the raw material using metal blades and a chopping motion, producing in shorter cellulose fibers and weaker paper. Today, modern paper mills use machines that are similar but use chemicals instead of blades to break down the wood. The Hollander beater was a huge improvement over previous methods for making paper. Before it was developed, paper had to be made by hand, one sheet at a time. The labor involved in making paper led to its high cost. But the Hollander beater reduced the cost of paper products because many papers could now be made from just one large piece of wood. This also helped conserve forest resources since fewer sheets needed to be made from each tree. People have been making paper for thousands of years using techniques that were not too different from what mill owners used today. Papermakers still use wood as a source of fiber today, only now they use mechanical processes instead of hand tools. And like their ancient counterparts, modern paper manufacturers collect the fibers from various sources (wood pellets, cotton, hemp, etc.) and combine them into a slurry called "stock" that is used by papermakers to make paper. When stock is poured into a papermachine it forms long strips of paper called "sheets".