Cha-no-yu (茶の湯 the tea ceremony) or Sadô (茶道 lit. the way of tea) was introduced to Japan from China and perfected by Master Sen-no-Rikyu (千利休) based on the spirit of Zen in the 16th century.
For Japanese people, cha-no-yu is a mental discipline for pursuing "wabi" (a state of mind in which a person is calm and content, with a profound simplicity) and is at the same time a performance in which form and grace are paramount.
A ceremonial tea-room is usually about three meters square (a four-and-a-half tatami-mat room) and is decorated very simply. The spirit of "wabi" is exemplified by this tea-room.
Nijiri-guchi: a side door about 60 cm square through which guests enter the tea-room. Since they are forced to bow when passing through this door, they naturally lose their sense of self-importance and become humble.
The style of cha-no-yu depends on the school, such as Ura-Senkê, Omotê-Senkê, etc. The style described above is primarily that of Ura-Senkê.