Landslides play an important role in the evolution of landforms and represent a serious hazard in many areas of the World. In places, fatalities and economic damage caused by landslides are larger than those caused by other natural hazards, including earthquakes, volcanic eruptions and floods. Due to the extraordinary breadth of the spectrum of landslide phenomena, no single method exists to identify and map landslides, to ascertain landslide hazards, and to evaluate the associated risk. This work contributes to reduce this shortcoming by providing the scientific rationale, a common language, and a set of validated tools for the preparation and the optimal use of landslide maps, landslide prediction models, and landslide forecasts.