Many file types are supported by Paraview. However, for beginers or users who generate the data sets by programming, it is always confused about the specific format of the supported input files and hard to organize the data structure in the input files. It would be great to have an input file format tutorial or guide in the Paraview website to help users create the supported data files.
Here are the specifications of the native file formats of VTK and ParaView: VTK File Formats - VTK documentation