Constraints is the academic concept and methodological approach concerned with identifying, characterizing, and analyzing the limitations, boundaries, or conditions that define the feasible operational space, possible states, or potential outcomes of a system, process, or model. This research area investigates how these restrictions, which may stem from fundamental physical laws, material properties, design specifications, or operational requirements, govern behavior, influence performance, and determine the inherent capabilities and limitations of complex systems. Understanding and managing constraints is fundamental to predicting system dynamics, optimizing design and operation, ensuring stability and safety, and assessing the feasibility of theoretical models and practical applications across various scientific and engineering disciplines.