Terra cotta , is a clay-based unglazed or glazed ceramic, where the fired body is porous.An appropriate refined clay is shaped into the desired shape. After drying it is placed in a kiln, or atop combustible material in a pit, and then fired. . It is suitable for in-ground use to carry pressurized water (an archaic use), for garden ware or building decoration in tropical environments, and for oil containers, oil lamps, or ovens. Most other uses such as for tableware, sanitary piping, or building decoration in freezing environments require that the material be glazed.