Tileset

From Mario Fan Games Galaxy Wiki

A tileset is essentially sprites that are tiled for use in computer and video games. In the past, graphics were stored in "tiles" and re-arranged in game to form a sprite. Usually these tiles would be in 8x8, 16x16 or 32x32 pixel dimentions that would then be used to make everything on screen. In fangaming, this method is simplified and usually only concerns backgrounds. Game Maker for example allows the user to manipulate tilesets to automatically add them to the game.

Tilesets are often distributed to the public in the form of sprite sheets (but are usually just called tilesets), which can then be easily manipulated afterwards. MFGG 2.0 added a category specifically for tilesets, as before then they were simply placed in the "backgrounds" category.