In game development, the term resource denotes an external component, which the application loads during runtime. Another often-used term for a resource is asset.
Mostly, resources are heavyweight multimedia items, such as images, music themes, or fonts. "Heavyweight" refers to the fact that those objects occupy a lot of memory, and that operations on them, especially copying, perform slowly. This affects the way we use them in our application, as we try to restrict slow operations on them to a minimum.
Non-multimedia items such as scripts that describe the in-game world, menu content, or artificial intelligence are also considered resources. Configuration files containing user settings such as the screen resolution and the music volume are good examples of resources as well. However, when we mention resources in the book, we mostly refer to multimedia resources.