From Jinja Honcho and Kokugakuin University. The table below shows two common types.
| Type | What it looks like |
|---|---|
| Myojin torii | The upper lintel curves upward. |
| Shinmei torii | It is unpainted, and its top lintel is straight. |
A torii is a gateway that shows the entrance to a sacred area. A jinja may have one torii or several. A jinja and its grounds are like the home of the kami, and when you pass through the torii you enter a sacred space.
Jinja Honcho says a torii stands for the border between the ordinary world and the sacred world. A torii also helps you tell a Shinto shrine from a Buddhist temple: each Shinto jinja has a torii at the entrance, and this is the main symbol that sets it apart from a temple. On a map, a torii mark usually means a Shinto shrine.
A typical torii has two upright pillars and two horizontal beams. The upper beam, called the kasagi, sticks out past the pillars on both sides. Under it, a second beam called the nuki goes through the pillars and joins them.
Torii are usually made of wood or stone, though other materials such as metal or concrete are also used. Some are painted vermilion. The style and materials can differ from one torii to another, but a torii is a clear sign that a jinja is there.
There are many styles. Two common types are the Myojin torii, with an upper beam that curves upward, and the Shinmei torii, which is unpainted and has a straight top beam.
When a jinja has several torii, the largest one at the start of the approach is usually called the first torii (ichi no torii). Torii may also stand inside the grounds, and they show that the place gets more sacred as you come closer to the main sanctuary.
The path that begins at the first torii and leads to the prayer hall is called the sando. Some sacred places, such as certain mountains, have no prayer hall or main hall. There, a torii stands at the entrance of the sacred area and shows that the kami is present.
Torii are not only at jinja. They are also found at some Buddhist temples, such as the famous stone torii of Shitennoji in Osaka.
Many people stop and bow their heads a little before they walk through a torii. Jinja Honcho says it is enough to treat the grounds with the respect you would show when visiting an important person in their home.
Once you have passed through the torii, you are in a sacred area. Please act in a way that fits the place, even if you are outside, in the woods or on the grass. After that, the path leads to the place where people pay their respects to the kami.
One famous example is the great torii of Itsukushima Shrine, on an island in Hiroshima Bay. It is vermilion and stands about 200 m offshore from the main shrine. At low tide, visitors can walk under it.
There is no single right answer. Talking it over with someone at home is a good way to learn.