A USB interface is the connection layer that lets a device communicate with a modern computer or controller. It carries data, and often power too, while the host identifies the attached device and decides how to talk to it. In embedded systems and retro hardware, USB often becomes the bridge between old components and new firmware, making it a key part of the design rather than a simple cable port.
In cybersecurity, USB matters because every attached device is a trust decision. A peripheral can pretend to be a keyboard, storage device, or network adapter, which gives attackers a way to inject input, copy data, or deliver malicious firmware. Defenders reduce risk with port controls, device allowlists, signed firmware, and monitoring for unusual USB behavior. In practice, the USB interface is both a convenience and an attack surface, especially when a small controller translates signals for hardware that cannot protect itself.