VisIt is a free, open source, platform independent, distributed, parallel, visualization tool for visualizing data defined on two- and three-dimensional structured and unstructured meshes. VisIt’s distributed architecture allows it to leverage both the compute power of a large parallel computer and the graphics acceleration hardware of a local workstation. VisIt’s user interface is often run locally on a Windows, Linux, or macOS desktop computer while its compute engine component runs in parallel on a remote computer. VisIt’s distributed architecture allows VisIt to visualize simulation data where it was generated, eliminating the need to move the data to a visualization server. VisIt can be controlled by its Graphical User Interface (GUI), through the Python and Java programming languages, or from a custom user interface that you develop yourself. More information about VisIt can be found online at https://visit.llnl.gov/.