As we run through the instructions in our mind, just like a computer, we create variables and assign them values.

We call all the variables the state.

An experienced programmer will be able to remember the state of the program as they read through it. In the beginning, it will help to write down the state as you execute the instructions in your head.

When a variable changes, update what you've written down and when a substitution is needed, you'll find it easier to get the value correct.

Another value that's part of state, is the current line number. This will change like a variable so it helps to write that down too until you can do that in your head.