You're here because you have a file that has a file extension ending in .vi. Files with the file extension .vi can only be launched by certain applications. It's possible that .vi files are data files rather than documents or media, which means they're not meant to be viewed at all.

A LabVIEW virtual instrument file contains source code and reference data used by a custom application that was developed using the LabVIEW software, and this means a LabVIEW virtual instrument file is initialized and executed to run the applet itself within the LabVIEW software. The content of a LabVIEW virtual instrument file is integrated with source code compilation standards proprietary to National Instruments, developer of the LabVIEW software. Data encoding specifications also proprietary to National Instruments and the LabVIEW software are also implemented into these LabVIEW virtual instrument files for storing its content in the VI file format. Affixed with the .vi extension, a LabVIEW virtual instrument file is usually created through the LabVIEW software for simulating the functions of physical instruments used for scientific data research and measurement analysis. The "VI" in the VI file format stands for "Virtual Instrument", and an example of a physical instrument that can be simulated by a LabVIEW virtual instrument application is an oscilloscope. These virtual instruments can be developed from VI templates loaded unto the LabVIEW application, or from scratch via the set of functionalities integrated into the LabVIEW software, a program developed for scientific data research and measurement analysis.

Launch a .vi file, or any other file on your PC, by double-clicking it. If your file associations are set up correctly, the application that's meant to open your .vi file will open it. It's possible you may need to download or purchase the correct application. It's also possible that you have the correct application on your PC, but .vi files aren't yet associated with it. In this case, when you try to open a .vi file, you can tell Windows which application is the correct one for that file. From then on, opening a  .vi file will open the correct application. Click here to fix .vi file association errors

Be careful not to rename the extension on .vi files, or any other files. This will not change the file type. Only special conversion software can change a file from one file type to another.

A file extension is the set of three or four characters at the end of a filename; in this case, .vi. File extensions tell you what type of file it is, and tell Windows what programs can open it. Windows often associates a default program to each file extension, so that when you double-click the file, the program launches automatically. When that program is no longer on your PC, you can sometimes get an error when you try to open the associated file.