*There are 14 digital pins in total, starting from 0 to 13.
*All pins from 0 to 13 can be used for digital inputs/outputs.
*pin 0 can be used as RX (receiver) and pin 1 can be used as TX (transmitter) which are required during communication with other arduinos.
*pin 13 has an led attached to it, which glows when the output of pin 13 is high.
*pins 3,5,6,9,10 and 11 can be used for PWM (pulse width modulation) (represented by “~” on arduino board).