What is a variable? Technically, it's a tiny section of your computer's memory that will hold any information that you put there. While a game is running, it keeps track of where the information is stored, the value kept there, and the type of that value. However, for this chapter, all you need to know is how a variable works. It's very simple.

What's usually in a mailbox, besides air? Well usually there's nothing, but occasionally there is something in it. Sometimes, there are letters, bills, a spider, and so on. The point is that what is in a mailbox can vary. Therefore, let's call each mailbox a variable.

In the game development world, some simple examples of variables might be:

• playerName
• playerScore
• highestScore

When we write a script, we are making lines of code that the computer is going to execute, one line at a time. As we write our code, there will be things that we want our game to execute more than once. For example, we can write a piece of code that adds two numbers. Suppose our game needs to add those two numbers a hundred different times during gameplay. So you'd say, "Wow! I have to write the same code a hundred times to add two numbers together? There has to be a better way."

Let a method take away your typing pain. You just have to write the code to add two numbers once and then give this chunk of code a name, such as AddTwoNumbers(). Now, every time your game needs to add two numbers, don't write the code over and over, just call the AddTwoNumbers() method.

The class plays a major role in Unity. Most of your code will be written inside classes. Think of it like a container for variables and methods.

You just learned about variables and methods. These two items are the building blocks used in Unity scripts. The term "script" is used everywhere in discussions and documents. Look for it in the dictionary, and you will see that it can generally be described as written text. Sure enough, that's what we have. However, since we aren't just writing a screenplay or passing a note to someone, we need to learn the actual terms used in programming.

Unity calls the code it creates a C# script. However, people like me have to teach you some basic programming skills and tell you that a script is really a class.

The Start(), Update(), and Awake() methods are called automatically. The Start() method is called on the frame when the script is enabled. For most of our components, this will be when you press the Start button in Unity.

The Awake() method is called just before the Start() method. That gives a very convenient place to set up code if you have any. The Update() method is very specific. It's called on every frame if the component is enabled. It's very useful for observing user keyboard actions, for example. As you can see in our script, in Line 16 we are checking on every frame to find out whether the user has pressed the Enter key.

Let's create a new C# script and call it LearningMethods. As you can see, the Start() and Update() methods are added automatically when you create a new script. To...

Our script has variables for holding data, and our script has methods to allow tasks to be performed. I now want to introduce the concept of communicating with other GameObjects and the components they contain. Communication between one component's GameObject and another component's GameObject using dot syntax is a vital part of scripting. It's what makes interaction possible. We need to communicate with other components or GameObjects to be able to use the variables and methods in other components.

When you look at code written by others, you'll see words with periods separating them. What the heck is that? It looks complicated...

The fundamental mechanism of programming is making decisions. In everyday life, we make hundreds and possibly thousands of decisions a day. They might be the results of simple questions such as "Do I need an umbrella today?" or "Should I drive at the maximum highway speed at the moment?" Let's first take a question and draw a single graph, as follows:

This is a fairly easy question. If it will be raining, I will need an umbrella; otherwise, I won't. In programming, we call it an if statement. It's a way we describe to the computer what code should be executed under what conditions. The question "Will it be raining?" is the condition. When planning your code, you should always break decision–making down into simple questions that can be answered only by a "yes" or a "no."