This paper provides a comprehensive overview of the conceptual framework for studying local adaptation, a process where populations evolve traits that are advantageous in their specific habitat, in contrast to other habitats. The authors review theoretical work on the interplay between divergent natural selection and gene flow, emphasizing the importance of low gene flow and strong selection against genotypes adapted to other habitats for local adaptation. They discuss reciprocal transplant and common garden experiments designed to detect local adaptation, highlighting the need for replication at the level of the deme (local population) to distinguish local adaptation from other forms of deme × habitat interactions. The paper also addresses the measurement of fitness and the minimization of non-genetic effects, such as maternal effects and environmental stress, to ensure accurate detection of local adaptation. Finally, it explores the processes driving local adaptation, including the agents of divergent selection, traits under selection, and the role of gene flow and other ecological factors. The authors advocate for multifaceted approaches that explicitly test hypotheses about the role of specific ecological and genetic factors in local adaptation, emphasizing the importance of experimental evolution in controlled environments.This paper provides a comprehensive overview of the conceptual framework for studying local adaptation, a process where populations evolve traits that are advantageous in their specific habitat, in contrast to other habitats. The authors review theoretical work on the interplay between divergent natural selection and gene flow, emphasizing the importance of low gene flow and strong selection against genotypes adapted to other habitats for local adaptation. They discuss reciprocal transplant and common garden experiments designed to detect local adaptation, highlighting the need for replication at the level of the deme (local population) to distinguish local adaptation from other forms of deme × habitat interactions. The paper also addresses the measurement of fitness and the minimization of non-genetic effects, such as maternal effects and environmental stress, to ensure accurate detection of local adaptation. Finally, it explores the processes driving local adaptation, including the agents of divergent selection, traits under selection, and the role of gene flow and other ecological factors. The authors advocate for multifaceted approaches that explicitly test hypotheses about the role of specific ecological and genetic factors in local adaptation, emphasizing the importance of experimental evolution in controlled environments.