Energy-efficient algorithms is a research area and methodological approach dedicated to the design, analysis, and optimization of computational processes to minimize the energy consumed during execution. This field investigates the intricate relationship between algorithmic structure, computational resources, and energy expenditure, extending traditional complexity analysis beyond time and space to include energy metrics. Key characteristics involve focusing on metrics such as energy per operation or total energy consumption, exploring techniques like reducing operations, optimizing memory access, and exploiting energy-aware hardware features. Its significance lies in enabling sustainable computing, extending device autonomy in battery-constrained environments, and reducing operational costs and environmental impact in large-scale computational infrastructure.