Ecological stoichiometry (ES) is the study of the balance of energy and multiple chemical elements in ecological interactions. While its foundation lies in studies of lakes and lake plankton, ES has expanded to include streams, soils, grasslands, forests, and other ecosystems. This article provides an overview of introductory articles, foundational papers, and papers on biochemical, evolutionary, and ecological applications of ES. The field remains highly dynamic, with over 6,100 citations per year in ISI Web of Science. The article covers the integration of diverse fields within ecology, such as physiological ecology, community ecology, and biogeochemistry, and the extension of ES to new realms like biochemical allocation, life history evolution, and cancer dynamics. Key topics include the "Growth Rate Hypothesis," which links C:N:P ratios to growth rate and RNA allocation, and the role of stoichiometric imbalances in nutrient recycling. Review papers discuss the extension of ES to stream and lake benthos, terrestrial ecosystems, and the generalization of the approach into a "resource ratio theory for consumers." Historical perspectives highlight the roots of ES in Liebig's Law of the Minimum, Lotka's work on population dynamics, and Redfield's seminal study on the stoichiometry of plankton. The article also explores biochemical and physiological determinants of organismal stoichiometry, including the role of organelles and structural materials. Evolutionary pressures shaping stoichiometry are discussed, with studies linking genome structure and elemental limitation. Causes of stoichiometric imbalances at the ecosystem level are examined, focusing on resource supply and demand mismatches. The consequences of stoichiometric imbalances are explored, including direct effects on consumers, competition, and trophic interactions. The article concludes with a discussion of how stoichiometric considerations can be integrated into theoretical population dynamics and food web models.Ecological stoichiometry (ES) is the study of the balance of energy and multiple chemical elements in ecological interactions. While its foundation lies in studies of lakes and lake plankton, ES has expanded to include streams, soils, grasslands, forests, and other ecosystems. This article provides an overview of introductory articles, foundational papers, and papers on biochemical, evolutionary, and ecological applications of ES. The field remains highly dynamic, with over 6,100 citations per year in ISI Web of Science. The article covers the integration of diverse fields within ecology, such as physiological ecology, community ecology, and biogeochemistry, and the extension of ES to new realms like biochemical allocation, life history evolution, and cancer dynamics. Key topics include the "Growth Rate Hypothesis," which links C:N:P ratios to growth rate and RNA allocation, and the role of stoichiometric imbalances in nutrient recycling. Review papers discuss the extension of ES to stream and lake benthos, terrestrial ecosystems, and the generalization of the approach into a "resource ratio theory for consumers." Historical perspectives highlight the roots of ES in Liebig's Law of the Minimum, Lotka's work on population dynamics, and Redfield's seminal study on the stoichiometry of plankton. The article also explores biochemical and physiological determinants of organismal stoichiometry, including the role of organelles and structural materials. Evolutionary pressures shaping stoichiometry are discussed, with studies linking genome structure and elemental limitation. Causes of stoichiometric imbalances at the ecosystem level are examined, focusing on resource supply and demand mismatches. The consequences of stoichiometric imbalances are explored, including direct effects on consumers, competition, and trophic interactions. The article concludes with a discussion of how stoichiometric considerations can be integrated into theoretical population dynamics and food web models.