Now that we have our first object in the scene, we can talk about 3D space—specifically, how an object's position, rotation, and scale behave in three dimensions. If you think back to high school geometry, a graph with an x and y coordinate system should be familiar. To put a point on the graph, you had to have an x value and a y value.
Unity supports both 2D and 3D game development, and if we were making a 2D game, we could leave our explanation there. However, when dealing with 3D space in the Unity Editor, we have an extra axis, called the z-axis. The z-axis maps depth, or perspective, giving our space and the objects in it their 3D quality.
This might be confusing at first, but Unity has some nice visual aids to help you get your head on straight. In the top-right of the Scene panel, you'll see a geometric-looking icon with the x, y, and z axes marked in red, green, and blue, respectively. All GameObjects in the scene will show their...