Tiles are a very common element in games, used to store information in a simple tesselated format. Because tile grids can easily represent the space of the entire screen, tiles are a very common means of organizing level structure.
The utility of tiles ranges from the layout of ground to hard restrictions on the movement of in-game entities. It may apply to only parts of the game such as overworld movement, or it could represent the entirety of all meaningful interactions in the game.
Questions under the purview of this tag involve subjects such as organizing tilesets, rendering the contents of tiles, and how to integrate freeform movement within tiled maps.