Biomass is biological material derived from living, or recently living organisms. It most often refers to plants or plant-derived materials which are specifically called lignocellulose biomass. As a renewable energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel. Conversion of biomass to biofuel can be achieved by different methods which are broadly classified into: thermal, chemical, and biochemical methods.
Historically, humans have harnessed biomass-derived energy since the time when people began burning wood to make fire. Even in today's modern era, biomass is the only source of fuel for domestic use in many developing countries.