A key card switch is a device that is installed in hotel rooms to control the electrical power supply to various devices in the room. The switch is activated by inserting the hotel key card into a slot next to the door. Once the card has been inserted, the switch allows the flow of electricity to the room, powering the lights, air conditioning, and other electrical devices. When the guest leaves the room and removes the key card the switch automatically turns off the power to the room. This helps to conserve energy and reduce the hotel's utility costs. This feature is often used as an energy-saving measure in hotels, helping to reduce unnecessary energy consumption and promote sustainability.