 Up to this point, we've been using Python as a glorified desk calculator. In arithmetic, you did calculations, then you moved up to algebra where you used variables. In a similar way, we're now going to move from calculations in Python to using variables in Python. Similar but not identical because variables in Python do not work exactly the same as variables do in algebra. Let's look at this statement in Python. You may be tempted to read it as x equal 42 because of that symbol in the middle, but what it really is saying is x refers to the value 42. As the book says, you should read that symbol in the middle as refers to gets or is assigned. The way Python evaluates this and the way you should evaluate it is to look at the value on the right-hand side first. Always, always, always start on the right-hand side. So that value 42 goes into memory somewhere. And then the variable on the left-hand side x refers to the value 42. Let's follow that with another statement. x refers to 7.3. Again, we start on the right-hand side. The value of the right-hand side is 7.3 and that gets put into memory. Then we look at the left-hand side and say x now refers to 7.3. The 42 is left around in memory and it'll eventually get cleaned up. What about using variables in further calculations? In this code, after the first statement is done, x refers to the value 7.3. In the second statement, y refers to x plus 1.2. We always, always, always start out with the right-hand side and figure out what it works out to. Well, what is x referring to right now? 7.3. That means we can substitute as 7.3 plus 1.2 and the right-hand side works out to 8.5 and that value goes into memory. Now and only now can we look at the left-hand side and find that the variable y refers to 8.5. So that's the status of memory at this point in our program. To drive home the point that the variables in Python don't work like the ones in algebra, let's look at this set of two statements. At the end of the first statement, x refers to 5. That's what the first statement says. But let's look at that second statement. In algebra, that doesn't make any sense at all. 5 doesn't equal 6. But again, this isn't algebra. Instead, you're going to follow the rule. Whenever you see that symbol in the middle, you will always go to the right-hand side first and work it out completely. What's in x right this moment? x right now refers to 5, so that substitutes to 5 plus 1, so the right-hand side works out to 6. Now and only now can I look at the left-hand side and say, who's referring to that 6? Answer, x. So x now refers to 6 instead of the 5. What we've done, by the way, is called incrementing x. You'll see this pattern. x refers to x plus 1, almost said equals there. x refers to x plus 1, or x is assigned x plus 1, a lot in Python and a lot in programming because it's very common to have computers do counting. The moral of the story, whenever you see something like that thing at the top, you read a variable refers to value, or a variable is assigned value, or variable gets value. You go to the right-hand side first and figure out what that value works out to. Once you've completely worked it out, then the variable on the left will refer to that value.