Which term describes the physical connection where independent systems communicate?

The term that best describes the physical connection where independent systems communicate is "interface." An interface serves as the point of interaction between different systems, allowing them to exchange data and communicate with one another. This interaction can occur through hardware connections, such as network cables, or through software-defined protocols that facilitate communication between systems, irrespective of their underlying architecture.

In the context of computing and networking, an interface is crucial because it establishes the protocol and format for data transfer, ensuring that independent systems can effectively understand and process the information being shared. This concept is foundational in networking, as it enables compatibility and communication between various devices, such as computers, routers, and switches.

While other terms have specific meanings in networking, they do not capture the same breadth that "interface" does in terms of describing a connection that enables communication. For instance, a router routes data between networks, packets are units of data transmitted across a network, and frames refer to data packets at the data link layer, encapsulating packets with a specific header and footer for transmission. However, none of these terms directly encapsulate the broader concept of the physical and logical connection necessary for independent systems to communicate effectively.