D-subminiature (D-sub) connectors were invented by Canon ITT in 1952 and are now in common use on a plethora of IT equipment. They have 2, 3 or 4 rows of pins (male) or sockets (female) surrounded by an elongated D-shaped metallic shell. The shell provides mechanical support and electrical screening and it's D-shape ensures correct plug and socket orientation. Connector contacts are spaced 2.74 mm apart with the rows spaced 2.84 mm apart.
Nomenclature
The correct format to specify a D-sub connector is shown below. The initial letter D (for D-subminiature) is followed by a letter denoting the shell size (A, B, C, D or E). A hyphen then preceeds two or three digits that are used to denote the number of pins. The final character is either P (plug) or S (socket) to denote the gender.
There are numerous examples of misused nomenclature in everyday use such as the DE-09 connector being commonly (and erroniously) being called a DB-9. Also, the final character is often either M (Male) or F (Female) instead of P or S. The hypen is often omitted.
D-subminiature connectors are divided into three groups; Standard Density, High Density and Double Density. The following tables show the correct names and the commonly-used names for all D-subminiature connectors.
Clicking on a pinout drawing will provide additional information about that particular connector.
D-subminiature (D-sub) Standard Density Connectors
| Shell | Pinout | Correct Name | Common Name | Pins | Rows |
| DA |
 |
DA-15 | DB-15 | 15 | 2 |
| DB |  |
DB-25 | DB-25 | 25 | 2 |
| DC |  |
DC-37 | DB-37 | 37 | 2 |
| DD |  |
DD-50 | DB-50 | 50 | 3 |
| DE |  |
DE-09 | DB-9 | 9 | 2 |
D-subminiature (D-sub) High Density Connectors
| Shell | Pinout | Correct Name | Common Name | Pins | Rows |
| DA |  |
DA-26 | DB-26HD, HD-26 | 26 | 3 |
| DB |  |
DB-44 | DB-44HD, HD-44 | 44 | 3 |
| DC |  |
DC-62 | DB-62HD, HD-62 | 62 | 3 |
| DD |  |
DD-78 | DB-78HD, HD-78 | 78 | 4 |
| DE |  |
DE-15 | DB-15HD, HD-15 | 15 | 3 |
D-subminiature (D-sub) Double Density Connectors
| Shell | Pinout | Correct Name | Common Name | Pins | Rows |
| DA |  |
DA-31 | DB-31DD, DD-31 | 31 | 3 |
| DB |  |
DB-52 | DB-52DD, DD-52 | 52 | 3 |
| DC |  |
DC-79 | DB-79DD, DD-79 | 79 | 3 |
| DD |  |
DD-100 | DB-100DD, DD-100 | 100 | 4 |
| DE |  |
DE-19 | DB-19DD, DD-19 | 19 | 3 |
Note: The P or S final character has been omitted from the above tables.