Unify doesn't produce any sound by itself. It relies on plug-ins to produce and modify sound. Unify includes a substantial set of plug-ins, some of which are actually built into the program, and can also work with just about any other plug-ins you own.
Unify can deal with three categories of plug-ins:
As you may know, plug-ins also come in various, mutually-incompatible formats. Unify can load any of the following three formats (Audio Units is Mac-only):
Unify itself comes as a stand-alone app and as a plug-in, in VST, VST3, and Audio Unit formats. (An AAX version of Unify may be available at some time in the future, but even it would not be able to load AAX plug-ins.)
Unify maintains a simple database of plug-ins it knows about, which includes details like the plug-in name, manufacturer name, format (e.g. VST, AU, etc.), and the path to the folder where the plug-in is stored.
You can inspect the contents of this database by clicking on the plug icon near the bottom-right corner of the Unify GUI (highlighted in blue-green in the following screenshot). This is called the plug-ins view. (Note some details, such as folder paths, don't appear in this view, but they are still present in the database.)
This plug-in database is automatically populated with details about Unify's built-in and bundled plug-ins, but other plug-ins on your computer must be registered with Unify, so it can add them to its database. This can be done in either of two ways: