What is a VST Plug-in?
Steinberg created the VST plugin standard and introduced it with their Cubase VST audio sequencer product line.
Quoting from the Steinberg VST SDK:
"In the widest possible sense a VST-Plug-in is an audio process. 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. Generally speaking, it can take a stream of audio data, apply a process to the audio and send the result back the host application. [...]: The host does not maintain any information about what the plug-in did with the last block of data it processed. From the host application's point of view, a VST Plug-In is a black box with an arbitrary number of inputs, outputs, and associated parameters. The Host needs no knowledge of the plug-in process to be able to use it."
