Computational Science is the use of computers to perform research in other fields. It is the application of computer simulation and other forms of computation to problems in various scientific disciplines. It is not to be confused with Computer Science which is the study of topics related to computers and information processing.

Computational Science is a new third mode of science, complimenting and adding to experimentation/observation and theory.

Scientists and engineers develop computer programs, application software, that model systems being studied and run these programs with various sets of input parameters. Typically, these models require massive amounts of calculations (usually floating-point) and usually run on supercomputers or a distributed computing platform.

Computational science application programs often model real-world changing conditions, such as weather, air flow around a plane, automobile body distortions in a crash, the motion of stars in a galaxy, an explosive device, etc. Such programs create a 'logical mesh' in computer memory where each item corresponds to an area in space and contains information about that space relevant to the model. For example in weather models, each item might be a square kilometer; with land elevation, current wind direction, humidity, temperature, pressure, etc. The program would calcuate the likely next state based on the current state, in simulated time steps, solving equations that describe how the system operates; and then repeats the process to calculate the next state.