Pig feeding and nutrition is a crucial aspect of pig farming, as it directly impacts growth, health, and productivity from birth to market weight. In this chapter the authors consider the key factors in the setting of nutritional guidelines, such as breed and genetic traits affecting nutrient and energy requirements, production goals, and growth stage and weight. Discussion then moves to how to formulate diets to maximise feed efficient and performance while still minimising nutrient excretion. Here the authors consider the diets of nursery pigs, growing-finishing pigs, boars, and gilts and sows. Finally, the authors examine the key challenges in formulating nutritional guidelines and their potential solutions. These challenges include heat stress, the presence of toxigenic fungi and mycotoxins in feed ingredients, post-weaning diarrhoea, and the potential detrimental effect of high dietary leucine concentration.