A state machine is good for modeling things that move in and out of states. For instance a car can go from being stopped to being driving, or from driving to crashing.
Today we're going to model my dog Baron. Let's assume Baron is very simple (although in reality he has quite complex feelings and emotions). Baron has a few basic states: sleeping, playing, and eating.
He does a few basic things to transition him into different states:
@baron.play
sleeping => playing
@baron.eat
playing => eating
@baron.sleep
eating => sleeping
Again, this is a simple representation, and we can add more states if we run out of things to do.