The Wood Wall is a placeable block that is used in the background. It does not block monsters from walking into the player's home. Along with a light source, it is used to prevent monsters from spawning in a player's home. Like all walls, it can only be broken with a hammer or a hamaxe. It can also be destroyed by using explosives.
Wood Walls are often used by starting players to create their starting house, as it is easy to obtain near the beginning of the game.