A D-sub contains two or more parallel rows of pins or sockets usually surrounded by a D-shaped metal shield that provides mechanical support, ensures correct orientation, and may screen against electromagnetic interference. The part containing pin contacts is called the male connector or plug, while that containing socket contacts is called the female connector or socket. The socket's shield fits tightly inside the plug's shield. The plug also may have screws on either side of the shield that fasten into holes in the socket (although sometimes the screws are on the socket: see the DE9 pictured to the left). When screened cables are used, the shields are connected to the overall screens of the cables. This creates an electrically continuous screen covering the whole cable and connector system.

There are now D-sub connectors which have the original shell sizes, but more pins, and their names follow the same pattern. For example, the DE15, usually found in VGA cables, has 15 pins in three rows, all surrounded by an E size shell. The pins are spaced at 0.090 inches (2.3 mm) horizontally and 0.078 inches (2.0 mm) vertically, in what is called High Density. The other connectors with the same pin spacing are the DE15, DA26, DB44, DC62, and DD78. Reflecting the same confusion of the letters DB with just D as mentioned above, these connectors are also often called DB15HD (or even DB15 or HD15), DB26HD, DB44HD, DB62HD, and DB78HD connectors, respectively, where HD stands for "high density". They all have three rows of pins, except the DD78, which has four. The "double density" series of D-sub connectors features even denser arrangements and consists of the DE19, DA31, DB52, DC79, and DD100. These each have four rows of pins.

A smaller type of connector derived from the D-sub is called the microminiature D, or micro-D, which is a trademark of ITT Cannon. It is about half the length of a D-sub.

There is yet another similar family of connectors that is easy to confuse with the D-sub family. These connectors have names like HD50 and HD68, and have a D-shaped shell that is about half the width of a DB25. They are common in SCSI attachments.

The original D-sub connectors are now defined by an international standard, IEC 60807-3 / DIN 41652. The United States military also maintains another specification for D-subminiature connectors, the MIL-DTL-24308 standard.