Answer!
Here it goes (a bit complicated):
1. A soundcard driver API (Application Program Interface) is used by audio software to access the hardware. Common APIs for sound- or audiocards are: MME (also called 'wave' or 'mmsystem'), DirectSound (sometimes called 'DirectX') or ASIO.
The four main APIs that are used with professional audiocards at the moment are: MME, DirectSound, ASIO and GSIF (GigaSampler-InterFace).
MME or 'Wave' API
The MME devices (or drivers) have been invented by Microsoft with the not very well known operating system called "Windows with MultiMedia Extensions 1.0" that was based on Windows 3.0 and was the base for later released Windows 3.1 and 3.11. The name of the OS ("MultiMedia Extensions") was also used for the API to access soundcards. Windows MME 1.0 was really the first Microsoft operating system that provided a universal API that worked with any soundcard hardware exactly the same way (if there was a driver). The same API with small modifications is used until today to playback and record wave audio.
If you go to Control Panel > Multimedia in any modern Windows version (95 and higher) you can select the prefered devices for audio playback and recording. These devices are representing the MME API of the soundcard driver. MIDI I/O is also handled via MME devices.
Hope this helps,
Wings