The cuprates – complex oxides of copper – are remarkable compounds that lose electrical resistance at record temperatures. Understanding the physics behind this high-temperature superconductivity would be of enormous fundamental and practical importance. Yet after more than three decades of truly remarkable research activity, the salient features of both the ‘normal’ state (above the superconducting transition temperature) and the superconductivity itself remain debated. In this work, a team of scientists from the University of Minnesota, Vienna University of Technology, Austria, and University of Zagreb, Croatia have developed a simple yet powerful phenomenological model that resolves several of the major open questions. Crucially, the model posits that the cuprates exhibit inherent inhomogeneity, as well as two co-existing electronic subsystems: localized and itinerant. These premises are strongly supported by a number of experiments, and naturally lead to a description of the normal state. Furthermore, the superconductivity is shown to arise from an interaction between the two subsystems. The model thus provides a clear framework for understanding the enigmatic cuprates.