A biofuel is a fuel that is produced through contemporary processes from biomass, rather than a fuel produced by the very slow geological processes involved in the formation of fossil fuels, such as oil. Since biomass technically can be used as a fuel directly (e.g. wood logs), some people use the terms biomass and biofuel interchangeably. Often however, the word biomass simply denotes the biological raw material the fuel is made of, or some form of thermally/chemically altered solid product, like torrefied pellets or briquettes. The word biofuel is usually reserved for liquid or gaseous fuels, used for transportation. The EIA (U.S. Energy Information Administration) follow this naming practice. If the biomass used in the production of biofuel can regrow quickly, the fuel is generally considered to be a form of renewable energy.
Biofuels can be produced from plants (i.e. energy crops), or from agricultural, commercial, domestic, and/or industrial wastes (if the waste has a biological origin). Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis.