Consider a circuit with a power supply, a lamp and two switches, A and B. These can be arranged to form a LOGIC circuit in the following way.

AND Circuit

AND switch circuit

It is clear that for the Lamp to be Lit or ON, then switch A AND switch B need to be ON. This arrangement is therefore known as an AND circuit. There are four possibilities of switch settings in the above circuit. A and B OFF, A OFF and B ON, A ON and B OFF and A ON and B ON.