VSTi Host is a Macintosh application that allows VST plugins to be used outside of larger host applications (like Cubase, Logic, etc.). It also allows for sequencers that may not have native support for VST plugins and/or instruments (like ProTools, Logic 6, Vision, Digital Performer, and Metro for example) to use them, as long as the sequencer supports the OMS-IAC bus (OS 9) or CoreMIDI (OS X).
