Wood

Wood is the material in trees produced by xylem cells, in distinction to the bark, which is produced by phloem cells, and the leaves and fruit of the tree. Wood is found in the trunk and branches of trees. Wood is widely used as a structural and artistic material.

Artistic use

Wood is widely used for practical and decorative arts. Until recently, most furniture was made from wood and cloth fabrics, and wood is a popular material for sculpture and other decorative pieces.

Structural use

Wood from many types of trees can be cut into pieces which retain their shape and strength after drying. Wood processed into shapes for use as building materials is called lumber. Not all trees produce wood suitable for lumber: some woods shrink irregularly, causing deformation of the cut piece, and others do not have sufficient strength or are too brittle for economic use.

As a structural material, wood has the advantages of being light, flexible, moderately strong, and easily produced. It has the disadvantages of being flammable, subject to attack by some insects and fungi, inhomogenous, subject to splitting, and of being limited in sizes and shapes. The majority of single-family houses in the United States are built using wood for at least some structural elements. Wood-framed houses are quite popular. Larger structures are less likely to be built using wood as a structural element, though structures up to four stories high completely framed in wood are common, and some long railroad bridges and tall roller coasters have been constructed primarily of wood.