Computational science is now commonly considered a third mode of science, complementing and adding to experimentation/observation and theory (see image on the right). Here, we define a system as a potential source of data, an experiment as a process of extracting data from a system by exerting it through its inputs and a model ("M") for a system ("S") and an experiment ("E") as anything to which E can be applied in order to answer questions about S. A computational scientist should be capable of: