RDP

RDP, the Remote Desktop Protocol, is a Microsoft protocol that lets a client connect to and fully control the graphical desktop of a remote Windows machine over a network. It ships the remote screen down to the client while sending keyboard, mouse, and redirected device input back up, so a user can work on a distant computer as if sitting in front of it. It is one of the most widely deployed remote-access protocols in enterprise IT.

• Graphical remoting - RDP streams the remote desktop’s display and relays local input, not just a text terminal session.
• Channel multiplexing - Virtual channels carry extras like clipboard, printer, audio, and drive redirection alongside the screen.
• Standard endpoint - Servers listen on TCP port 3389, which is also why exposed RDP is a well-known attack surface.
• Client ubiquity - Native clients exist across Windows, macOS, Linux, and mobile, making it a default for remote administration.

RDP is infrastructure rather than an API standard, but it matters to the same operations teams. Because an exposed RDP port is a favorite target for credential-stuffing and ransomware, it belongs behind VPNs, bastions, and gateways, and its posture is exactly the kind of network-surface signal that security and governance reviews look for. In practice it sits adjacent to the API estate — the remote-access rails admins use to reach the very servers that host APIs — which is why locking it down is part of a defensible operational baseline.