A switchboard is a device that connects telephone calls by plugging wires into different sockets to create circuits between callers. Before phones could automatically connect calls, human operators sat at large panels covered with holes called jacks and cables with plugs on each end. When someone wanted to make a call, they'd pick up their phone and an operator would answer. The caller would say who they wanted to talk to, and the operator would physically plug a cable from the caller's jack into the receiver's jack, creating a direct connection between the two phones.

In the early 1900s, switchboard operators worked in rooms filled with these massive boards, quickly plugging and unplugging hundreds of cables to connect calls all day long. The job required excellent memory, fast hands, and a calm voice. Most operators were young women, and the work was considered highly skilled. By the 1960s, automatic switching technology made most switchboard operators obsolete, though some businesses and hotels still use smaller switchboards today.

The word also describes any central control panel that routes electrical connections. A theater's lighting switchboard lets technicians control different stage lights, and some buildings have electrical switchboards that manage power distribution. The core idea remains the same: one central place where connections are made and unmade.