I am wanting to get to arduinos to communicate with each other. I have heard of i2c and pwm signal and that pwm can be transmitted from an fm transmitter. What is the best communication method for wired and wireless communication. I have heard of xbees and other wireless communication modules but would like to build my own transmitters and receivers. Also if any one could explain to me how i2c and pwm SIGNAL work it would be appreciated.
Any help will appreciated.