Innovation is indispensable for firms and national economies to maintain their international competitiveness. Consequently, the capacity to measure innovation activities and outcomes, thereby enabling corporate management and public policymakers to steer innovation processes deliberately, has acquired renewed urgency. Building on contemporary theoretical advances, this chapter offers a structured review of the most prevalent measurement approaches at both macroeconomic and firm levels. At the national level, it discusses traditional input-oriented indicators, such as R&D expenditure and human capital, outcome indicators, such as patent statistics and high-technology export shares, and composite indexes exemplified by the Global Innovation Index. At the corporate level, the survey covers product, process, organizational, and marketing innovations, drawing on the Oslo Manual, community innovation surveys, and balanced scorecard extensions. Methodological strengths and limitations were assessed with respect to data availability, sectoral comparability, time-lag effects, and the ability to capture nontechnological innovation. This review reveals persistent blind spots, notably in measuring service innovation, digital platform ecosystems, and open innovation interactions across organizational boundaries. The chapter concludes by delineating a future research agenda that prioritizes dynamic multidimensional metrics that are capable of integrating social and environmental impacts into innovation performance.