Clearance or control of pathogens or tumors usually requires T‐cell‐mediated immunity. As such, understanding the mechanisms that govern the function, maintenance, and persistence of T cells will likely lead to new treatments for controlling disease. During an immune response, T‐cell development is marked by striking changes in metabolism. There is a growing appreciation that these metabolic changes underlie the capacity of T cells to perform particular functions, and this has led to a recent focus on the idea that the manipulation of cellular metabolism can be used to shape adaptive immune responses. Although interest in this area has grown in the last few years, a full understanding of the metabolic control of T‐cell functions, particularly during an immune response in vivo, is still lacking. In this review, we first provide a basic overview of metabolism in T cells, and then we focus on recent studies providing new or updated insights into the regulation of metabolic pathways and how they underpin T‐cell differentiation and memory T‐cell development.