UMX610 - What are VST instruments and VST effects?
VST stands for Virtual Studio Technology. VST effects and instruments take the form of plugins for your DAW. These plugins can be used in more or less the same way that hardware MIDI instruments and effects are used. For example, you can send MIDI note data to a synthesizer VST instrument the same way you can send MIDI note data to a hardware synth. VST effects can also be used in a similar fashion to inserts, and can also be adjusted with MIDI data.