Fast-setting is a requirement for many mortars such as adhesives for natural stones or large format ceramic tiles, tile grouts or self-leveling underlayments. Understanding the mineralogical and technical principles of fast-setting systems is crucial for the design of high-quality mortars and special concretes such as those based on alternative cementitious materials (ACMs). Therefore, this paper provides a twofold overview, a theoretical from the mineralogical perspective, and a practical from the application perspective. In the tetrahedron CaO-(Al,Fe)2O3-SiO2-SO3 a majority of fast-setting systems can be located in a narrow room. Therefore, this tetrahedron is predestinated for a simple graphical overview on the different singular, binary and ternary fast-setting binder systems. From the practical perspective the many additional material properties (e.g., fast drying, shrinkage compensation), which are related to fast-setting mixed binder systems are of great interest. Thus, developing fast-setting mortars or concretes needs a concept to balance the required material properties in a designed formulation.