- At SparkFun, we do a lot of stuff over serial.

- Once upon a time, most of the interfaces to Really Serious Computers -- the
  ones at universities and in government -- worked like debugging Arduino
  code over a serial port.

- The computer prints stuff, you type stuff to the computer, the computer
  prints stuff.  It's just text in a box.

- Even once we got PCs in our houses, a lot of the interfaces shared this
  heritage.  Remember DOS?  Ever have to fire up cmd.exe on Windows?