The role of system architecture in software engineering is to define the structured framework and overall design of a software system. It encompasses key components, their interactions, and the principles governing the system's organization. A well-defined architecture ensures that system requirements are met, balances performance, scalability, and maintainability, and aligns with business goals. It serves as a blueprint for development and guides critical decisions regarding technology choices, design patterns, and integration strategies. Ultimately, effective system architecture is essential for delivering high-quality software that meets user expectations and adapts to changes.