Background walls

Walls are tiles that create backgrounds, most being usable as items. Natural walls make up the background of most biomes, and placed walls are an essential part of a house. All placed walls prevent enemies from spawning, and a room filled with "safe walls" is necessary in order to attract NPCs or to use a bed to set the spawn point. Naturally occurring walls are considered unsafe until the player tears them down and re-places them (if they can be harvested).

Walls may be removed with a Hammer, but walls that weren't placed by a player have to be torn down from the edge (i.e., there must be at least one adjacent tile with no wall).

Natural walls and backgrounds:
 * At positive elevations (see layer), Dirt Walls are the mainstay of the map. Dirt walls must therefore be removed from either the top or bottom edges of the zone of positive elevation, making the construction of safe houses in the center of the dirt zone a fairly lengthy task.
 * At negative elevations, the backdrop of the map is no longer dirt and walls of the player's choice may be placed on the backdrop freely.

Other notes:
 * Torches and many furniture items can be placed on walls. See Decorative items → Wall section for an overview.
 * Walls don't have any monetary value, not even those made out of higher tier ores like gold.
 * As of version 1.2, a wall can be crafted back into the crafting material it was made from. This is done a 4 to 1 ratio (the opposite of the "to walls" ratio). In other words, a Cloud can make 4 Cloud Walls which combined can remake the Cloud.

[[File:Hive Wall.png]] Naturally Occurring Walls
These walls are spawned when the new world is created, and can all be obtained by some method.

Obsidian Back Wall.png Unobtainable Walls
These walls are spawned when the world is created but are unable to be created, obtained, looted, purchased, or used by the player in any way*. They can be destroyed, but drop nothing (with one exception).
 * Unobtainable walls can be utilized with third-party map editors such as TEdit.

Rainbow_Wallpaper.png Purchased Walls
These walls are purchased from various NPCs.

Hallowed Grass Wall.png Converted Walls
These walls are mainly created when the Corruption, Crimson, or Hallow naturally spreads to them, but they can also be made by using the respective Solution with the Clentaminator. When destroyed, these walls do not drop anything. This technically makes them unobtainable.

Wooden Fence.png Crafted Walls
These walls are made by the player using various crafting materials.