A summary is given of the development of an improved method to handle powder diffraction data. The resulting method, now called the Rietveld method, uses powder diffraction step-scanned intensities instead of integrated powder intensities. This enables the full use of the information content of a powder diagram. The method has revitalized the use of powder diffraction in structure determination. An unexpected and later development is the use of the method in quantitative phase analysis. This is now an essential tool in many industrial processes.