The study of materials by diffraction methods started about 100 years ago with the pioneering experiment of Laue, Friedrich and Knipping, when the first X-ray diffraction patterns of single crystals were obtained (Friedrich et al., 1912). This was the beginning of a rapid development fostering many diffraction-based methods and techniques, which is still continuing. The measurement of rocking curves and the associated derived quantitative parameters, such as the ‘full width at half-maximum’ (FWHM) of the curves, has been performed since at least 1921 (Davis & Stempel, 1921) by exploiting the X-ray diffraction (XRD) properties of crystals. Since then, this has become one of the most powerful methods for the diffraction-based characterization of crystalline materials. The experimentally closely related method of X-ray diffraction imaging or X-ray diffraction topography has been used since about 1931 (Berg, 1931). Soon after World War II, the requirements of the electronics industry for the nondestructive analysis of defects in semiconductor materials like silicon and germanium (and others) boosted the improvement of these methods to their modern high-resolution variants like high-resolution X-ray diffraction and in particular high-resolution and high strain sensitivity X-ray topography (Bond & Andrus, 1952; Lang, 1957). This evolution was additionally accelerated in the late 1970s by the use of synchrotrons as dedicated X-ray sources and later on, starting in the 1990s, by the use of third-generation synchrotron sources.