A VST Plug-in is not an
application. It needs a host application that handles the audio streams and
makes use of the process the VST plug-in supplies. VST / VST3 plugins run
within a digital audio workstation (DAW), to provide additional
functionality, though a few standalone plugin hosts exist which support
VST/VST3. VST/VST3 plugins are either instruments (VSTi) or effects (VSTfx).
VST/VST3 plugins provide a custom graphical user interface that displays
controls similar to physical switches and knobs on audio hardware.