Introduction to decals and projection

Decals are materials that decorate the surface of other materials. They are most commonly used for effects like paint splatters and stickers.

Unity projects these materials into a sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary so that they wrap around other scene geometry. This means that you can also use them for effects that simulate projected light, such as blob shadows.