MiniDisc (MD)
A Sony Walkman MiniDisc player (in the middle) surrounded by MiniDiscs and tape players. (Photo by Orin Zebest under a CC BY 2.0 license.)

The MiniDisc (MD) is an obsolete magneto-optical disc-based data storage device for 74 minutes and, later, 80 minutes, of digitized audio or 1 gigabyte of Hi-MD data. The Sony brand audio players were on the market from September 1992 until March 2013.

Source: Wikipedia