Now, the next question is what exactly do we mean by entropy? Well, let's look at diagram A and diagram B. In diagram A, we have a situation in which this container is our system, and the molecules inside are also part of our system. Now, in this particular case, we have this artificial barrier, or door, if you will, that essentially prevents the molecules from this side going into this side. So all the six molecules and each molecule carries a certain amount of energy are essentially localized or concentrated on the left side of our container. Now, as soon as we open that door, what exactly happens?