Computational science is a discipline focused on the design, implementation and use of mathematical models or simulations through the use of computers to analyse scientific problems, systems or processes. Computational science heavily relies on computational technologies such as high performance computing, artificial intelligence, computational intelligence, grid infrastructure and parallel computing. Geocomputation is closely related to computational science and, therefore, geocomputational methods are often derived from machine learning, clustering, simulation, parallel computing and high performance computing. Contrary to the methods and tools applied for spatial analysis described under the Analytical Methods Knowledge Area, geocomputation methods may involve spatial methods available in standard GIS packages, but quite often require self-development, or at least customisation, involving computational technologies to solve target problems. The aim of this topic is to provide an introduction to computational science with particular emphasis on its usage and relation to geocomputation.