To reduce dependency on fossil fuels, there is tremendous interest in using biomass feedstocks for producing fuels, heat, power, chemicals, and bio-products. Biomass feedstocks such as corn stover and switchgrass are often collected in baled forms, which involve a lot of handling, storage, and transportation costs because of low bulk density of bales. Densification of biomass feedstocks into briquettes and pellets can reduce the cost and increase the efficiency of handling, storage, transportation, and use of biomass feedstocks. This book provides the fundamentals of densification mechanisms of biomass feedstocks studied using a laboratory-scale densification apparatus, a pilot-scale roll press briquetting machine, a pilot-scale ring-die pelleting machine, and constitutive modeling. This book reveals that the NATURAL BINDERS in the biomass feedstocks such as lignin, protein, starch and sugars can be activated using moisture and temperature (steam) to manufacture high quality briquettes and pellets without adding chemical additives (binders). This book is a very useful resource for briquetting and pelleting industries as well as biomass densification researchers.