This appendix presents lists of important words and most commonly used symbols related to biomass. The increasing importance of biomass as a renewable energy source has led to an acute need for reliable and detailed information on its assessment, consumption and supply. Traditional biomass is obtained from wood, twigs, straw, dung, agricultural residues, etc. Biomass is burned directly for either heat or to generate electricity, or it can be fermented to alcohol fuels, anaerobically digested to biogas or gasified to produce high-energy gas. The chapter also presents basic concepts related to energy units and some conversion figures of wood, fuelwood and charcoal. Energy can be measured in different units, among which the most generally used is joule. The energy content of commercial energy sources is expressed by the calorific values, which give the energy content of the given material related to the unit of weight, measured in kJ/kg.