Fuente: Broccoli Byproducts Extraction This chapter comprehensively explores plant proteins, establishing them as essential, sustainable, and nutritionally sound alternatives to animal-based sources. It commences by examining their varied sources and categories, encompassing legumes, oilseeds and nuts, pseudo-cereals, and green leaves, with a focus on their distinct nutritional profiles and compositions. Key aspects such as amino acid composition, digestibility, and factors affecting bioavailability are thoroughly discussed. Also, the critical functional properties of plant proteins, detailing their significance in food formulation through characteristics such as emulsification, solubility, water-holding capacity, and gelling behavior, are discussed. Furthermore, the presence of anti-nutritional factors is acknowledged, and various extraction and modification strategies are outlined, including enzymatic hydrolysis, chemical, and physical treatments, all designed to improve protein quality and broaden application potential. The chapter also highlights the inherent advantages of integrating plant proteins into diets and industrial applications, while frankly confronting the current challenges in their widespread adoption. By presenting both processing innovations and the wider environmental and ethical considerations, this discussion underscores the central role of plant proteins in cultivating robust, health-promoting food systems and advancing sustainable food technology.