# Unique TFS Concepts

### Cylinder

A cylinder is defined as any sort of container which can contain items inside of it.

List of what can be defined as a cylinder:

* Container
* Tile
* Inventory slots

### Thing

Although not a class, a `thing` generally encapsulates any unique thing such as an item or creature in the game which is able to be manipulated.

List of what can be defined as a thing:

* Players
* Monsters
* NPCs
* Items
* Tiles
* Containers