This chapter compares closed and open innovation approaches as strategies for firms—especially small and medium-sized enterprises (SMEs)—to remain competitive in a globalized, fast-changing market. The closed innovation model relies on internal R&D and strict protection of intellectual property, resulting in longer development times and limited access to external knowledge. In contrast, open innovation encourages collaboration with external partners such as customers, suppliers, and research institutions, enabling faster technological progress and greater creativity. While open innovation offers advantages like shorter time to market and enhanced adaptability, it also entails risks related to intellectual property and partner dependency. The chapter concludes that open innovation, through its Outside-In, Inside-Out, and Coupled modes, provides a more flexible and effective framework for SMEs and large firms to co-create value and sustain growth in dynamic markets.