Prompt engineering, initially an intuitive process, becomes increasingly complex and unpredictable as AI applications scale, necessitating a shift towards a systematic engineering discipline that emphasizes testing, measurement, and optimization. Unlike traditional programming, where changes yield predictable effects, prompt modifications can lead to unforeseen consequences, such as hallucinations or format compliance issues. To address this, successful AI teams approach prompt development with clear requirements, modular architectures, and data-driven evaluation frameworks that include automated scoring and prompt versioning. This systematic approach enhances reliability and adaptability by enabling rapid iteration, reducing technical debt, and ensuring that AI features perform consistently across diverse inputs and evolving requirements. By mastering systematic prompt engineering, teams can build robust AI applications that maintain high performance in production environments, providing a competitive advantage over those relying on ad-hoc methods.