Chapter Eight focuses on the powder diffraction pattern—the direct result obtained from a powder diffraction experiment, which serves as a cornerstone of basic materials characterization, particularly in diffraction analysis. The chapter addresses the origin, representation, and interpretation of the powder pattern—an assumedly simple one-dimensional dataset, where diffracted intensity is a function of the diffraction angle 2θ. To deepen understanding, this chapter presents a detailed analysis of the powder diffraction pattern in terms of three key aspects: (1) peak position — primarily determined by the unit cell dimensions and crystal symmetry, (2) peak intensity — principally dependent on the crystal structure, and (3) peak shape — influenced by both specimen characteristics and instrumental parameters.