The DB-9 is a type of electrical connector commonly used in computer and communication equipment. It features nine pins arranged in two rows and is often used for serial communication, allowing devices to exchange data. The connector is part of the D-subminiature family, which includes various sizes and configurations. DB-9 connectors are typically found in older RS-232 serial ports, which were widely used for connecting peripherals like modems and printers. Although modern technology has shifted towards USB and other interfaces, DB-9 connectors are still relevant in specific applications, particularly in industrial and legacy systems.