Local adaptation is an evolutionary process whereby populations develop traits that enhance their survival and reproduction (fitness) in their specific local environment relative to individuals originating from other environments, driven by natural selection acting differentially across heterogeneous landscapes. It constitutes a central concept and active research area within evolutionary ecology and population genetics, investigating the genetic mechanisms, ecological factors, and evolutionary trajectories leading to population divergence and optimized performance under specific local conditions. Hallmarks include genetic differentiation among populations, empirical evidence of selection favoring local genotypes, and often, reduced performance of non-local genotypes in a given environment. The study of local adaptation is critical for understanding biodiversity patterns, predicting species responses to environmental change, and guiding effective conservation and management strategies.