MME (Windows)
Windows' oldest audio interface, dating from the 1991 Multimedia Extensions – still listed in every DAW's driver menu as the option nobody should pick.
Microsoft added sound and MIDI to Windows 3.0 through the Multimedia Extensions add-on, which was then folded into Windows 3.1. The programming interface is waveOut and waveIn: the application hands buffers to the system and gets told when they have been played. It is simple, works with every sound card that ever had a Windows driver, and has therefore outlived everything that came after it.
The price is latency. Today MME goes through the same shared audio engine as everything else and often adds several tens of milliseconds – fine for system sounds, useless for playing a software instrument. DirectSound, Kernel Streaming, WASAPI and ASIO all exist largely to get around it. It still sits at the top of the list because it is the only one guaranteed to work.