Lumber, also known as timber, is wood that has been processed into beams and planks, a stage in the process of wood production. Lumber is mainly used for structural purposes but has many other uses as well.

Lumber may be supplied either rough-sawn, or surfaced on one or more of its faces. Besides pulpwood, rough lumber is the raw material for furniture-making, and manufacture of other items requiring cutting and shaping. It is available in many species, including hardwoods and softwoods, such as white pine and red pine, because of their low cost.^[1]

Finished lumber is supplied in standard sizes, mostly for the construction industry – primarily softwood, from coniferous species, including pine, fir and spruce (collectively spruce-pine-fir), cedar, and hemlock, but also some hardwood, for high-grade flooring. It is more commonly made from softwood than hardwoods, and 80% of lumber comes from softwood.^[2]