The GameMaker Studio 2 Room Editor permits you to add sprites into any given room using layers. As the name implies, a layer is simply a collection of assets that are all considered to be at the same depth within the room, and by stacking layers you can make some things draw over or under others. You can also control certain aspects of layers from code, adding or removing things, or changing certain properties of the layer or what it contains at run time. Below is a list of all the functions that can be used for editing sprite layers (also known as asset layers):