The torii is the gateway marking the entrance to a Shinto shrine and, more broadly, the boundary between ordinary space and the sacred precinct where kami are present. In its basic form it is two upright posts carrying two horizontal lintels, the upper one often curving upward. To pass beneath it is to cross from the profane into the consecrated; visitors conventionally bow and keep to the side rather than the centre, which is reserved for the kami.
Two broad families of form are distinguished by that upper lintel: the shinmei type, with a straight, unadorned crossbeam and no curve, associated above all with the Ise Grand Shrine, the most revered site in Shinto, and the myojin type, with an upswept lintel and often further ornament, which is the more common form at shrines generally. Torii are frequently erected in the sea or at the foot of a mountain, marking a whole landscape feature as sacred ground: the shrine island of Miyajima carries one of the best known, standing in tidal water off the coast, and near Ise the paired rocks called Meoto Iwa, Husband and Wife Rocks, are joined by a sacred rope with a small torii set at the shoreline before them, treating the rocks themselves, not a building, as the object of reverence.