Torii (鳥居) are formalized gateway arches signifying the transition from the mundane world to a sacred area. Shrines may have one or multiple torii. When multiple torii are present, the largest one is usually called the ichi no torii (一ノ鳥居, the first torii), and stands at the approach to the overall shrine. Torii may also be found at various points within the precincts to indicate increasing levels of holiness as you approach the honden (本殿, main sanctuary).

Torii first appeared in Japan around the mid-Heian Period (794-1185) and were probably introduced to Japan from Tang China via Korea as Buddhism spread east. It is believed that torii originated in India from the torana gates in the monastery of Sanchi in central India.

Torana, also known as vandanamalikas, are free-standing arched gateways in the Hindu, Buddhist, and Jain architecture fo South, Southeast, and East Asia. In addition to Japaense torii, Chinese páifāng gateways (牌樓), Korean hongsalmun (홍살문, 紅箭門), and Thai sao ching cha (เสาชิงช้า) have their roots in the Indian torana.

A torii is usually formed from two upright hashira, (柱, posts) topped by a horizontal shimagi (島木, tie beam) and kasagi (笠木, cap beam) that extends beyond the posts on either side; beneath the kasagi a horizontal nuki '(貫, tie beam) is mortised through the uprights, linking them together. At the center of the nuki there may be a supporting strut called gakuzuka (額束), sometimes covered by a tablet carrying the name of the shrine. Based on this elemental form, a variety of formal styles are found at shrines, depending on the overall style of shrine architecture employed and the character of the central saijin (祭神, deity) enshrined within.