Scenes contain the objects of your game. They can be used to create a main menu, individual levels, and anything else. Think of each unique Scene file as a unique level. In each Scene, you will place your environments, obstacles, and decorations, essentially designing and building your game in pieces.
Use the method described in the last section to create a Prefab. You can also read more details about Prefabs here. Once you’ve created a Prefab, you can quickly and easily make copies of the Prefab, called an Instance. To create an instance of any Prefab, drag the Prefab from the Project View to the Hierarchy or Scene View. Now you have a unique instance of your Prefab to position and tweak as you like.
When you have a Prefab or any GameObject highlighted, you can add additional functionality to it by using Components. Scripts are a type of Component. To add a Component, just highlight your GameObject and select a Component from the menu. You will then see the Component appear in the Inspector of the GameObject. Scripts are also contained in the menu by default.
If adding a Component breaks the GameObject’s connection to its Prefab, you can always use from the menu to re-establish the link.
Once your GameObject is in the scene, you can use the Transform Tools to position it wherever you like. Additionally, you can use the Transform values in the Inspector to fine-tune placement and rotation. Please view the Transform Component page for more information about positioning and rotating GameObjects.
Cameras are the eyes of your game. Everything the player will see while playing is through one or more cameras. You can position, rotate, and parent cameras just like any other GameObject. A camera is just a GameObject with a Camera Component attached to it. Therefore it can do anything a regular GameObject can do, and then some camera-specific functions too. There are also some helpful Camera scripts that are installed with the Scripts package. The Scripts package can be included when you create a new project, or you can use the menu. The scripts that you import can be found in from the menu. There are some additional aspects to cameras which will be good to understand. To read about cameras, view the Camera component page.
Except for some very few cases, you will always need to add Lights to your scene. There are three different types of lights, and all of them behave a little differently from each other. The important thing is that they add atmosphere and ambience to your game. Different lighting can completely change the mood of your game, and using lights effectively will be an important subject to learn. To read about the different lights, please view the Light component page.