This chapter explores the approach to designing a processor core optimized for a specific application. It covers different types of processors, their efficiency, performance trade-offs, and the importance of processor modeling. Performance profiling techniques and architectural exploration are discussed to tailor the processor design for specific computational needs. The chapter also highlights essential tools, design steps, and the role of SDKs in enabling efficient software-hardware co-design. Finally, it examines application-specific processors with real-world examples showcasing performance and efficiency improvements.