GiD is an interactive graphical user interface used for the definition, preparation and visualization of all the data related to a numerical simulation. This data includes the definition of the geometry, materials, conditions, solution information and other parameters. The program can generate a mesh suitable for several numerical methods (finite element, finite volume or finite difference, particle based or meshless methods) and write the information for a numerical simulation program in its required format. It is also possible to run these numerical simulations from within GiD and then visualize the results of the analysis.

GiD can be customized and configured by users so that the data required for their own solver modules may be generated. These solver modules may then be included within the GiD software system.

The program works, when defining the geometry, in a similar way to a CAD (Computer Aided Design) system. One characteristic is that the geometry is constructed in a hierarchical mode. This means that an entity of higher level (dimension) is constructed over entities of lower level; two adjacent entities will then share the same lower level entity.

All materials, conditions and solution parameters can be defined on the geometry itself, separately from the mesh as the meshing is only done once the problem has been fully defined. The advantages of this are that, using associative data structures, modifications to the geometry can be made and all other information will automatically be updated and ready for the analysis run. All this information can also be linked to Groups instead of geometry, so as all the entities (geometry and mesh) included in the group inherit it.

Advanced visualization tools (stereoscopic view, use of shadows, mirror effect, etc...) are used in order to provide the user with the best view of the model in order to get a better understanding of the 3D geometry of the model and the results of the simulation. Furthermore, snapshots or animations of the model using any visualization mode and including results can be exported in several formats with the desired resolution.

Full graphic visualization of the geometry, mesh and conditions is available for comprehensive checking of the model before the analysis run is started. More comprehensive graphic visualization features are provided to evaluate the solution results after the analysis run. This postprocessing user interface can also be customized depending on the analysis type and the results provided.