Wood is a solid material derived from woody plants, notably trees but also shrubs. Wood from the latter is only produced in small sizes, reducing the diversity of uses.
In its most common meaning, "wood" is the secondary xylem of a woody plant, but this is an approximation only: in the wider sense, wood may refer to other materials and tissues with comparable properties.
Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. Wood is composed of fibers of cellulose (40%–50%) and hemicellulose (15%–25%) held together by lignin (15%–30%).
Wood has been used for millennia for many purposes. One of its primary uses is as fuel. It is also used as for making artworks, furniture, tools, and weapons, and as a construction material.
Wood has been an important construction material since humans began building shelters, houses, boats. Nearly all boats were made out of wood till the late 1800s. It remains in common use today for some boats and houses. In buildings made of other materials, wood will still be found as a supporting material, especially in roof construction and exterior decoration. Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber will usually refer to felled trees, and the word for sawn planks ready for use will be timber.
Wood unsuitable for construction in its native form may be broken down mechanically (into fibres or chips) or chemically (into cellulose) and used as a raw material for other building materials such as chipboard, engineered wood, hardboard, medium-density fibreboard (MDF), oriented strand board (OSB). Such wood derivatives are widely used: wood fibres are an important component of most paper, and cellulose is used as a component of some synthetic materials. Wood derivatives can also be used for kinds of flooring, for example laminate flooring.
Wood is also used for cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon.