A relay is a switch which can be controlled through a digital signal. This is a board mount DPDT DC mechanic relay. There are 2 separate channels, each channel has NO (Normal Open), COM (Common), NC (Normal Closed) terminals.
When the input logic voltage is applied to the coil, the NC will disconnect from the COM breaking the conductivity between the two. At the same time the NO will connect with the COM allowing conductivity between them. Depending on your wiring this will turn on or off the connected load.
