Rye (Secale cereale L.) is a resilient cereal grain recognized for its distinctive nutritional attributes and potential health advantages. This chapter emphasizes on the comprehensive physical and chemical composition of rye, starting with its botanical features and morphological characteristics, which influence its milling and processing properties. The analysis highlights the grain's macronutrient profile, including carbohydrates, proteins and lipids, alongside its notable dietary fiber content. Additionally, it is examined for its rich mineral and vitamin content, which includes essential micronutrients such as phosphorus, magnesium and various B vitamins. The chapter also emphasizes the presence of bioactive compounds, particularly phenolic acids, that are associated with numerous health benefits, including antioxidant and anti-inflammatory effects. By synthesizing recent research findings, this chapter aims to enhance the understanding of rye's compositional characteristics and its implications for food science and nutrition, supporting its potential role as a functional food in promoting health and sustainable dietary practices.