Technology Readiness Levels (TRLs), pioneered by NASA, provide a structured framework for assessing the maturity of technologies, bridging the critical gap between research and real-world deployment. From their origins in aerospace to adoption across defense, energy, healthcare, automotive, and software sectors, TRLs enable organizations to measure progress, manage risk, and align innovation with operational goals. Complementary metrics such as Manufacturing Readiness Levels (MRL), Integration Readiness Levels (IRL), and System Readiness Levels (SRL) extend the framework to production, integration, and holistic system assessment, while emerging approaches incorporate AI, digital twins, and continuous monitoring to address nonlinearity, complexity, and ethical considerations. By expanding the concept of readiness to include societal, ethical, and sustainability dimensions, TRLs evolve into a comprehensive philosophy of progress — guiding technologies from concept to deployment in ways that are reliable, responsible, and human-centered.