VST and similar technologies use digital signal processing to simulate traditional recording studio hardware in software.
Thousands of plugins exist, both commercial and freeware, and many audio applications support VST under license from its creator, Steinberg.
Most VST plugins are either instruments (VSTi) or effects (VSTfx), although other categories exist—for example spectrum analyzers and various meters.
VST plugins usually provide a custom graphical user interface that displays controls similar to physical switches and knobs on audio hardware.
VST instruments include software simulation emulations of well-known hardware synthesizers and samplers.
This lets musicians and recording engineers use virtual versions of devices that otherwise might be difficult and expensive to obtain.
They released it at the same time as Steinberg Cubase 3.02, which included the first VST format plugins: Espacial (a reverb), Choirus (a chorus effect), Stereo Echo, and Auto-Panner.
VST Instruments can act as standalone software synthesizers, samplers, or drum machines.
It includes a preview version of VST3 for Linux platform, the VST3 part of the SDK gets a dual license: "Proprietary Steinberg VST3" or the "Open-source GPLv3".
FXpansion offers a VST-to-RTAS (Real Time AudioSuite) wrapper that lets VST plugins run in Pro Tools, and a VST-to-Audio Units wrapper lets VST plugins run in Logic Pro.
Origin from Arturia is a hardware DSP system that houses several VST software synthesizers in one machine, like Jupiter 50/80 from Roland.
Using appropriate software, audio data can also be sent over a network, so the main host runs on one computer, and VST plugins on peripheral machines.
In addition, Steinberg has developed the VST GUI, which is another set of C++ classes, which can be used to build a graphical interface.