The European energy system is undergoing rapid structural change, driven by the accelerating integration of renewables and the electrification of multiple sectors. As these developments increase operational complexity, the ability to coordinate distributed assets across electricity, heating, and mobility becomes essential for ensuring reliability and efficiency. Flexibility, defined as the capability to adjust generation, consumption, or storage in response to external signals, is becoming a foundational element of the evolving energy landscape. This talk addresses the central role of flexibility in enabling this transition. It explores how flexibility is defined in operational terms, why it is critical for system stability and cost-efficiency, and how it is being deployed through advances in digitalization, storage, and demand-side participation. Emphasis is placed on emerging flexibility provision technologies, market mechanisms, and regulatory shifts that are beginning to shape a more responsive and resilient energy system across Europe. The outlook for Morocco is also discussed, with a focus on the opportunities and challenges related to renewable integration and flexibility deployment in a rapidly evolving national context.