Immunometabolism is an emerging field that delves into the complex relationship between the immune system and metabolic processes. This chapter describes the fundamental aspects of immunometabolism, highlighting its significance in explaining the complex mechanisms underlying immune system function and its potential for therapeutic interventions. The long-held belief that immunity and metabolism are distinct systems with separate roles has been challenged in recent years, with growing evidence suggesting a strong link between the two systems. We discuss the bioenergetically demanding nature of immune processes and their distinctive metabolic pathways. Furthermore, we examine signaling and transcription pathways that regulate the activation of both the immune system and the metabolic pathways, underscoring the importance of these common pathways in primary immune regulation. We further explain how dysregulation of normal metabolic pathways contributes to cancer, autoimmunity, and other disease states, and possible treatment approaches based on metabolic intervention in immune cells. Overall, this chapter provides a comprehensive overview of the emerging field of immunometabolism, highlighting the intricate interplay between immunity and metabolism and its potential to enhance our understanding of the immune system and develop therapeutic applications for clinical intervention in the future.