Millets are nutrient-dense and climate-resilient cereals of the Poaceae family that flourish in arid and semiarid regions. This chapter elaborates on the origin, taxonomy, and domestication of millets, with a focus on major millets—pearl millet, finger millet, and sorghum—and minor millets like foxtail, proso, barnyard, kodo, and little millet. These grains generally possess higher nutritional values with quality proteins, dietary fibers, essential minerals, and bioactive compounds, thus holding great promise for tackling malnutrition and ensuring food security globally. Their physiological resilience, short growth cycles, and low inputs make them suitable and sustainable options over conventional cereals. In this chapter, their industrial applications regarding functional foods and nutraceuticals have also been discussed. Millets, therefore, contribute to and stand at the core of sustainable agriculture and climate-smart food system development.