A file with a .vts extension is associated with an open source application called PaarView by Kitware, Inc., which was designed to enable the viewing of large data sets. The .vts extension is used for structured grids or curvilinear data sets.
ParaView is an application designed to be used in conjunction with VTK, or Visualization Tool Kit, another widely used open source program. VTK uses an XML-based file format to produce 3-D computer graphics and image processing functions as well as data visualization.
ParaView adds user-friendly functionality to VTK, including a point-and-click interface. The differentiation of file extensions, including the .vts extension, allows the user to choose what data set attributes to load.