Dimensional lumber is a term used for lumber that is cut to standardized width and depth specified in inches. Carpenters extensively use dimensional lumber in framing wooden buildings. Solid dimensional lumber typically is only available up to lengths of 24 ft (7.32 m). Engineered wood products, manufactured by binding the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials, offer more flexibility and greater structural strength than typical wood building materials.
(Note) 2x4s are not actually 2 inches by 4 inches. When the board is first rough sawn from the log, it is a true 2×4, but the drying process and planing of the board reduce it to the finished 1.5×3.5 size. Here are the common sizes of lumber, and their actual sizes.