While wood is the most abundant natural material on Earth, it is also one of the most valuable. Its use is widely spread across the globe, with more than half of all roundwood consumed as fuel in less developed nations. In recent years, wood consumption per person has increased by an impressive rate, and this number is expected to surpass the levels of developed countries by 2030. But while wood is an invaluable resource, its availability is insecure because of depletion of many forests, resulting in a constant and expensive demand. The chemical composition of wood varies by species. The average wood contains approximately 50 percent carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 5% other elements. The other components of wood are calcium, potassium, sodium, magnesium, iron, silicon, phosphorus, and other minerals. The percentage of each element varies, but they are typically low. Regardless of species, wood is usually classified as either clear, medium, or brown. In ancient times, humans used wood as a fuel and in some cases, for construction. Historically, people have used wood to build their huts and homes, and it continues to be a popular material for furniture and other products. While we no longer use wood as a fuel, wood is still used for building and construction. In rural areas, many people still use wood to heat their homes. Compared to coal or gas, hardwood burns cleaner and longer. While wood is an expensive material to work, it also provides a warm and inviting atmosphere in a home.