Remember the following important points about what we learnt in this chapter:

• A relay is used to interface the Arduino board (or other micro-controller devices running on DC power) with AC powered equipment
• The positive end of the AC electric supply is connected to the COM port of a relay
• The positive end of the AC powered equipment is connected to the NO port of a relay
• The IN/IN1 port of a relay is used to accept a signal from Arduino, based on the signal the relay either switches ON (closed state) or OFF (open state)
• The digitalRead function is used to read input signals via Arduino's digital pins
• The digitalWrite function is used to send output signals via Arduino's digital pins.