In our Thang Component System architecture, the Thangs are the units, the things, the actors, the entities. A Thang can be an ogre, a rock, an arrow, a land, an invisible obstacle, a goal trigger--whatever. Thangs are specific to Levels and have just three properties:
id: the Thang's unique name within the LevelthangType: a pointer to a ThangType in the database, which holds all the art and sound information needed to display the Thang, but which has no impact on the Level's World simulation itself.components: a list of Components and their configuration, which together determine everything about how the Thang behaves in the game engine.
A very simple Thang might be a land. Let's look at a default Dungeon Floor Thang. Its id might be "DungeonFloor3" if there were a few other floors placed before it. Or you could rename it to "Top Left Floor"--doesn't matter, as long as it's unique. Its thangType will point to the latest Dungeon Floor ThangType. And it'll just have three Components:
Represented as JSON, these Components are simply:
[
{"original":"524b4150ff92f1f4f8000024","majorVersion":0,
"config":{"stateless":true}},
{"original":"524b7aff7fc0f6d519000006","majorVersion":0},
{"original":"524b75ad7fc0f6d519000001","majorVersion":0,
"config":{"pos":{"x":10,"y":30,"z":1},"width":20,"height":20,"depth":2,"shape":"sheet"}}]
A more complex Thang might have 20+ Components, and its ThangType might have many animations and sounds associated.