Cross-layer design is an academic concept and methodological approach within systems engineering and related fields that investigates and exploits the interactions, dependencies, and potential trade-offs between traditionally distinct abstraction layers (e.g., hardware architecture, operating system, middleware, application protocols, algorithms). This approach breaks from strict layered models by enabling information exchange and control across layer boundaries to achieve global system optimization, often balancing multiple conflicting objectives such as performance, power consumption, and resource utilization.