Wood is an organic material with fibrous, heterogeneous and anisotropic texture produced from the tree, which is a living organism. Wood is one of the oldest building material. Humankind uses wood for sheltering and protection purposes since the ancient times. Today, the wood has increased in value due to the decrease in forests for various reasons, the inability to grow new trees instead of those cleared away or due to the late growth of trees. Wood is used as roof fittings, woodwork and coating material and as loadbearing or decorative materials in models and scaffolding. Furthermore, there are also artificial building materials such as chipboard, MDF and plywood that are produced from woodchips, sawdust and dust, which are by-products of wood.

Take a tree and peel off the outer "skin" or bark and what you'll find is two kinds of wood. Closest to the edge there's a moist, light, living layer called sapwood packed with tubes called xylem that help a tree pipe water and nutrients up from its roots to its leaves; inside the sapwood there's a much darker, harder, part of the tree called the heartwood, which is dead, where the xylem tubes have blocked up with resins or gums and stopped working. Around the outer edge of the sapwood (and the trunk) is a thin active layer called the cambium where the tree is actually growing outward by a little bit each year, forming those famous annual rings that tell us how old a tree is.