The D-Subminiature or D-Sub is a common type of connector mainly used in computer industry for various purposes.
There are various types of D-Subs but most familiar one is DA-15 used for video display.

Types od D-Sub-s:

• DA-15 (joystick port, display port)
• DB-25 (serial port, serial communication)
• DC-37 (used in industrial products)
• DD-50 (used in industrial products)
• DE-9 (used for game controllers on Amiga, Commodore, Atari ...)

Although DB-25 is still used in recording studio industry others are mainly obsolete. The most used DA-15 is replaced by DVI port,
and others parallel and serial ports are replaced by USB, SATA, FireWire....