Commonly used for bathroom, shower/tub walls and kitchen backsplashes, wall tile has a highly porous body that is an important factor for proper bonding between the tile and vertical surfaces. Wall tile is suitable for interior applications only as it is not expected to withstand excessive impact or be subjected to freezing weather (freeze-thaw conditions). Almost any tile, including tiles designated as "floor" tiles, may be used for wall applications, but tiles that are designated as "wall" tiles should not be used on floor applications, only wall applications. Tiles that are designated for use on walls only are made from wet clay, rather than compressed dry clay, are are normally only fired, or baked once (floor tiles are baked twice for additional structure and durability), which makes them weaker and more brittle and unable to support heavy foot traffic.