This chapter summarizes the development and achievements of the GSHAP and the compilation of the Global Seismic Hazard Map. The Global Seismic Hazard Assessment Program (GSHAP) was designed to provide a useful global seismic hazard framework and to serve as a resource for national and regional agencies, by coordinating national efforts in multi-national regional-scale projects, by reaching a consensus on the scientific methodologies for seismic hazard evaluation and by ensuring that the most advanced methodologies are available worldwide through technology transfer and educational programs. Seismic hazard is defined as a probabilistic measure of earthquake ground shaking at a given location. The assessment of seismic hazard is the first step in the evaluation of the seismic risk, obtained by combining the seismic hazard with local site effects (anomalous amplifications tied to soil conditions, local geology, and topography) and with the vulnerability factors (type, value, and age of buildings and infrastructures, population density, land use, date and time of the day). The GSHAP Global Seismic Hazard Map is the first reference map for seismic hazard on a global scale, expressing the probability of ground shaking in a parameter of engineering interest (PGA), and the first obtained by the close collaboration of the scientists responsible for national seismic hazard zonations.