D-sub connectors (D-SUBminiature connectors) A family of plugs and sockets widely used in communications and computer devices. For example, the common analog VGA interface for monitors uses a D-sub 15-pin plug and socket. Also called "DB connectors," D-sub connectors come with 9, 15, 25, 37 and 50 pins. The D-sub defines the physical structure of the connector, not the purpose of each line.