A PoE switch (Power over Ethernet) is a network switch that carries data along with power over network cables. For example, the digital security camera that you install in your home or office requires two connections.
First is the network connection that which allows communication with video recording and display equipment.
Second is the power connection which carries the electricity required by the camera for its operations.
However, a PoE enabled camera eliminates the need for two connections as power is transferred over the network cable.