Basically, keys that are pressed on the remote are translated into infrared light signals that your TV can understand. The remote contains a chip that can tell which button has been pressed. The chip then sends out a Morse code like signal. Transistors inside the remote amplify the signal and a LED (Light Emitting Diode) translates the signal into infrared light, which is picked up by the TV. The TV then acts appropriately, either changing channel or altering the volume or whatever you asked it to do via the remote control.