external interface (1) A connection to a device outside the computer's cabinet. Contrast with internal interface.
(2) A connection to the WAN side of a router. The WAN may be a public or private network. Contrast with internal interface.

External Interfaces. It is useful to identify any external interfaces that are used by the product to communicate to the outside world. These interfaces may be used for a number of purposes, from simply connecting to peripherals (such as mouse, monitor, keyboard, desktop computer) to field programming or upgrading.

What are external interfaces?

External interfaces are typically a product's lifeline to the outside world. Such interfaces may be used for a number of purposes, including connecting to peripherals, field programming, or testing during product manufacturing. Typical interfaces include FireWire, USB, RS232, Ethernet, or JTAG IEEE 1149.1.

According to Richard Thayer (2002), "External interface requirements specify hardware, software, or database elements with which a system or component must interface...." This section provides information to ensure that the system will communicate properly with external components.