Introduction:

The world’s population is projected to grow to 9.1 billion people by 2050 (FAO, 2009a).  It is obvious that urgent action is required to ensure increased food supply and food security considering the restricted land resources. Food security has grown more important on both the international and domestic fronts as a result of the global supply, economic growth, and rising population in emerging countries. Two of the largest difficulties facing the modern world are addressing hunger and feeding the planet’s population. Conflicts, insufficient production of food resulting in imbalances in supply and demand, and shortages in the supply of micro- and macronutrients are some of the causes of this problem causing global instability in a number of places. The concept of food security encompasses both sustained access to wholesome nutrition as well as consistent access to physical food availability. Food insecurity is first divided into two categories by the Food and Agriculture Organization (FAO): moderate (limited access to food results in poorer dietary quality, eating patterns, health, and wellbeing) and severe (running out of food, experiencing hunger, and having health and wellbeing at severe risk) security (Food and Agriculture Organization, 2019). The threat of climate change and global warming persists even while some of these causes of hunger can be addressed, resulting in a marginal decrease in the number of people suffering from hunger and malnutrition from about one billion in 1990–1992 to 850 million in 2010–2012 (FAO,2012). Estimates indicated that by 2050, 2-3 billion people may experience hunger and other food and nutritional insecurities due to the decline in food production rates and the additional burden of feeding a population greater than 9 billion (Wheeler and Braun, 2013). Crop yields, crop production, and the overall sustainability of our food systems are all said to be directly impacted by climate change and rising world average temperatures. At both the macro and micro levels, ensuring food and nutrition security for India’s enormous and diverse population is a challenge, and work has been done on numerous fronts. There is no question that significant efforts have been undertaken recently to achieve food and nutrition security in India, and the advancements made cannot be disputed. However, unless concerted efforts are made, food insecurity and malnutrition appear to be continuing and may continue in the near future. So, the goal of sustainable improvement in food and nutrition security continues to be the main objective. According to some estimates, a few places may gain from climate change because of higher production and yields, but this won’t be enough to feed the growing population around the world (Downing et al., 2000). Furthermore, the majority of scientists concur that crop output would be severely decreased by the current rates of global warming and greenhouse gas emissions. Therefore, ensuring food security depends greatly on reducing greenhouse gas emissions in order to control global temperatures. However, one of the main sources of greenhouse gases like methane in the environment is the agriculture industry. Intensive agricultural practises, which are practised in various parts of the world, typically result in higher emissions (Olesen et al., 2002). In addition to being a large source of macronutrients including carbohydrates, lipids, and proteins, cereal crops also have a sizable potential to contribute to global warming. Wheat has the biggest global warming potential of all the major cereal crops, with an estimated 4 tonnes CO2eq/ha, followed by rice and maize (an estimated 3.4 tonnes CO2 eq/ha). Additionally, the carbon equivalent emissions from these crops are considerable, with an average of 1000, 956, and 935 kg C/ha for wheat, rice, and maize, respectively (Jain et al., 2016). They are widely cultivated and the main sources of nutrition for the entire world’s population despite having greater emission rates. Other minor cereal crops, including millet and sorghum, have significantly lower carbon footprints. This is one of the primary reasons why millets could be one of the crops that reduce the global carbon footprint (Prasad and Staggenborg,2009). Improved nutritional security can alsobe achieved by diversifying the agricultural system and using drought-resistant crops. A class of coarse grain cereals known as millets can be very helpful in achieving this. Millets are a group of diverse small-grain cereal crops grown belonging to the Poaceae grass family and are considered one of the oldest cultivated crops. They are composed of up to a dozen crop species, mostly from developing nations in Asia and Africa (Gupta et al., 2017). Despite significant pressure from competing crops in terms of regulations and production support, India is the world’s largest producer of millets, generating approximately 40% of the millets consumed worldwide. Ninety-seven percent of millet is produced in developing nations, making millet significant crops in the semiarid tropical regions of Asia and Africa (Vinoth and Ravidran, 2017).In temperate, subtropical, and tropical latitudes, the crop is primarily farmed on marginal lands in arid locations. The crop is preferred because of its yield and brief growth season in hot, dry conditions. Throughout human history, millet have played a significant role as a staple meal, especially in Asia and Africa. Since millets are C4 plants, they have a much more efficient photosynthetic system than C3 plants like rice and wheat. The majority of millet grains are now commonly referred to as “Nutri-cereals” because they have higher protein, fibre, calcium, and mineral contents than the widely consumed grains of rice and wheat. For the past 10,000 years, East Asia has been cultivating them. Millets are native to many regions of the world, and pearl millet is the variety that is grown the most widely. It is a significant crop in India and several regions of Africa (Lu et al., 2009). The most significant varieties include foxtail, finger, proso, and pearl millet. Millets could be crucial functional foods for the prevention of non-communicable diseases because they are a rich source of antioxidants, fibre, and essential and non-essential amino acids, vitamins, and minerals.This review aims to provide detailed provides detailed nutritional composition and its benefits to humans and livestock, need of growing millets, various constraints and perspectives associated with it.