Biomass refining constitutes the sustainable processing of biomass into a spectrum of marketable products and energy. The key technological contents of the major is treatment of biomass with tailored mechanical, chemical, biochemical and thermochemical processes leading to selective and efficient fractionation of the biomass components into functional fractions, and further refining of the fractions to fibres, polymers, chemical compounds and fuels or their reactants. The focus point of the major is the physiological function and structure of plants as well as the reactivity of the chemical components of lignocellulosic biomass in the conversion processes.