Hybrid photon counting (HPC) detectors have radically transformed basic research at synchrotron light sources since 2006. They excel at X-ray diffraction applications in the energy range from 2 to 100 keV. The main reasons for their superiority are the direct detection of individual photons and the accurate determination of scattering and diffraction intensities over an extremely high dynamic range. The detectors were first adopted in macromolecular crystallography where they revolutionized data collection. They were soon also used for small-angle scattering, coherent scattering, powder X-ray diffraction, spectroscopy and increasingly high-energy applications. Here, we will briefly survey the history of HPC detectors, explain their technology and then show in detail how improved detection has transformed a wide range of experimental techniques. We will end with an outlook to the future, which will probably see HPC technology find even broader use, for example, in electron microscopy and medical applications.This article is part of the theme issue `Fifty years of synchrotron science: achievements and opportunities'.