Effect plugins receive digital audio and process it through to their outputs. VST instruments receive notes as digital information via MIDI, and output digital audio. This lets musicians and recording engineers use virtual versions of devices that otherwise might be difficult and expensive to obtain.
These typically emulate the look of the original equipment as well as its sonic characteristics. VST instruments include software simulation emulations of well-known hardware synthesizers and samplers. Some (often older) plugins rely on the host application for their user interface. VST plugins usually provide a custom graphical user interface that displays controls similar to physical switches and knobs on audio hardware. Most VST plugins are either instruments (VSTi) or effects (VSTfx), although other categories exist-for example spectrum analyzers and various meters. VST plugins generally run within a digital audio workstation (DAW), to provide additional functionality, though a few standalone plugin hosts exist which support VST.
