Raising global consciousness about the environmental and economic problems resulted from overconsumption of non-renewable resources led to utilization of renewable biomass toward useful forms of biobased products. Such sustainable practice was driven by the extraordinary advancement in the biotechnologies. Wide spectrum of crops, agricultural residue, forest products, algae, and wastes were used as biorefining raw materials for biobased products such as biofuel, biochemicals, compost, and supplementary nutrition. In general, biomass feedstocks were classified into four generations, namely edible, inedible, algae, and genetically modified crops.  However, the extensive use of first generation of edible biomass in biorefinery systems led to food security issues, reduced arable soils, and increased consumption of water and fertilizer resources, making the overall footprint of using first generation feedstock less environmentally sustainable. In contrast, the second generation of inedible waste and the third generation of algal biomass are promising alternatives since they offer affordable feedstocks that neither compete with the food resources nor have a negative impact on the environment. In these frame points, this chapter explores the four generations of biorefining feedstocks, discusses the biotechnologies used to utilize biorefining feedstocks into added-value bioproducts and commodities, and delves into techno-economic analysis and future prospects in the pursuit of encouraging the sustainable practices.