Different types of construction projects call for different kinds of timber, and many people are familiar with the concepts of hardwood and softwood. However, few people know why woods are split into these two categories, and make the assumption that hardwoods are hard, while softwood is soft. This distinction is incorrect: balsa wood, for example, is classified as a hardwood despite the fact that it is very soft and light. Softwood and hardwood are actually distinguished botanically, not by their end use or appearance.

In general, hardwood comes from a deciduous tree which loses its leaves annually, and softwood comes from a conifer, which usually remains evergreen. Hardwoods tend to be slower growing, and are therefore usually more dense, but not always. Softwood usually grows in huge tracts of trees which may spread for miles, while hardwoods tend to be found mixed with a variety of other species.

Softwood comes from a type of tree known as a gymnosperm. Gymnosperms reproduce by forming cones which emit pollen to be spread by the wind to other trees. Pollinated trees form naked seeds which are dropped to the ground or borne along the wind so that new trees can grow elsewhere. Some examples of softwood include pine, redwood, fir, cedar, and larch.

A hardwood is an angiosperm, which means that it makes enclosed seeds or fruits. Angiosperms usually form flowers to reproduce. Birds and insects attracted to the flowers carry the pollen to other trees, and when fertilized the trees form fruits such as apples or nuts and seeds like acorns and walnuts. Hardwoods include maple, balsa, oak, elm, mahogany, and sycamore.

Both hardwood and softwood are used for everything from crucial structural beams to decorative accents. Some woods within each category are favored for particular uses: maple and elm are common elements in hardwood flooring. Redwood is often used for decking and other outdoor applications because the wood is naturally insect resistant and does not need to be treated with dangerous chemicals. Balsa is used for models and lightweight wood projects because it is easy to work with.

When picking out wood for any project, there are a few things to look for, regardless as to whether the wood is a hardwood or a softwood. The wood should have a tight, even grain without excessive knots or changes in pattern, unless it is being used decoratively. The wood should also not have any cracks or splits, and should be milled along the grain so that it will be strong. Be wary of staining and discoloration, which may represent exposure to water that could result in rot later.