Earlier guidelines such as ICH Q2(R1) and USP <1224>, <1225>, and <1226> viewed analytical method validation as a discrete activity focused primarily on chromatographic procedures. With ICH Q14, ICH Q2(R2), and USP <1220>, a life-cycle approach now ­considers variability and improves reliability, supported by tools like DoE, multivariate ­statistics, and digital technologies enabling Quality by Design and risk-based systems.