Walls are tiles that create backgrounds. Most wall types are items that can exist in player inventories, and can be placed by players in any area that doesn't already have background walls. Walls placed by players prevent enemies from spawning, and a mostly unbroken background of placed wall tiles is necessary for a structure to qualify as a House for attracting NPCs, or to place a Bed that can set a player's spawn point. Walls can be removed with a Hammer.
Walls can be found naturally in several Biomes. Naturally occurring walls will not stop enemies from spawning, and cannot be utilized for Houses. They must be torn down and placed manually in order for a House to occupy the space. All naturally occurring walls must be removed by starting from their edge (i.e., there must be at least one adjacent tile with no wall), unlike player-placed walls, which can be removed from any point.
Walls are generally obtained via crafting, purchasing from NPCs, or by harvesting naturally-occurring walls. One item of crafting material generally crafts four of its corresponding Wall items. As of version 1.2, four of the same Wall item can also be crafted back into one of the item it was made from.
- Dirt Walls generally completely cover the background at Underground depths above zero (see Layer, Depth Meter). Placing new walls in this area would require first tearing down the existing walls starting from the top (the Surface) or the bottom (zero depth), which can be an arduous task.
- At depths below zero, the backdrop of the map is generally no longer covered with actual Wall tiles, though this can be difficult to differentiate visually since the background image at these depths can have a similar appearance. Walls can be placed freely here by players.
- Torches and several other furniture items can be placed directly on background Walls without requiring blocks below them. See Decorative items → Wall section for an overview.
- Walls have no coin value, even if they were crafted from rare materials.
 Naturally Occurring Walls
These walls are spawned when the new world is created, and can all be obtained by some method.
 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.
 Purchased Walls
These walls are purchased from various NPCs.
 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.
 Crafted Walls
These walls are made by the player using various crafting materials.
 See also
- Adding walls made from Gemspark Blocks, Palm Wood, Boreal Wood, 1.2.3-Heavy Workbench-products, and Glass+Confetti.
- The Pirate now sells the Sail.
- Two natural cave walls (7 and 8) have been added. Gemstone Cave- and Moss Cave-walls have received an overhaul.
- The Metal Fence has been split into Lead and Iron variants.
- The Lavafall Wall and Waterfall Wall are now crafted like most other walls.
- Painted walls show up properly on the map.
- 1.2.3: Adding Dynasty Walls, Lavafall Wall, Waterfall Wall, even more Wallpaper, and the Portable Cement Mixer for even heftier wall placing.
- 1.2.2: Ten new holiday-themed wall types called Wallpaper can now be purchased from the Painter.
- 1.2.1: Fixed an issue causing walls to not have different frames. Pumpkin Wall, Hay Wall, and Spooky Wood Wall added.
- Lihzahrd Wall added.
- You can now craft living wood walls.
- Snow particles will no longer spawn on backwalls.
- 1.1.1: Added Snow Brick Wall, Candy Cane Wall, Green Candy Cane Wall
- 1.1: Added Glass Wall, Planked Wall, Mythril Brick Wall, Cobalt Brick Wall, Mudstone Brick Wall, Iridescent Brick Wall and Pearlstone Brick Wall.
- 22.214.171.124: Walls that are automatically placed to fill small gaps are now correctly taken from the player’s Inventory.
- 1.0.6: When placing background walls, one-block holes are now automatically filled in.