littleBits NOR

The NOR module is a logic gate with two inputs. As its name suggests, it sends an on signal only when neither input is receiving an on signal. In other words, it’s the exact opposite of the OR module. The NOR module is good for projects in which you want the output to be on unless one or both of its inputs are triggered.
Real World Example
A washing machine has two sensors. One to check if the washing machine lid is open and the other to sense whether the water in the washing tub is filled to minimum level. If either or both of these inputs are activated, the washing machine will stop.