Following this, we use it for testing besides debugging. What it does is that it establishes virtual hardware conditions of that of an Android or iOS device. We support operating systems that not even Microsoft and Apple themselves support anymore, such as macOS X on PowerPC Macs, and RetroArch being available on Windows OSes as far back as Windows 95. An Android or iOS application or a browser gets emulated by an emulator on an operating system considered as a defined one, such as that of Mac and Windows.
RetroArch can run on the usual platforms like Windows, Mac OS X and Linux, but it stands alone in that it can support far more platforms beyond just that.