A floor covering made of tightly woven grass and straw. A standard tatami is a rectangular mat about 1.82 m (≒6') long × 92 cm (≒3') wide × 5.25 cm (≒2") thick. However, dimensions vary to some extent according to the geographical location. A tatami mat made from rice straw is very tightly woven. This is covered with tightly woven rush grass that makes a very smooth surface. Each of the long sides are bound with cloth. Black, dark blue or brown cloth is often used in ordinary homes, but in elegant mansions and in some temples the binding is made of a type of damask. It is beautifully woven with gold, silver and other colored silk threads. Tatami are resilient when walked upon. Slippers are never worn on tatami. When bedding, futon, is laid upon the tatami, it provides a very comfortable place to sleep. The bedding is removed in the morning to a special storage place leaving a tatami room free for daytime use.
In the ancient period, there was no tatami of the type familiar today. Rather, there were simple sleeping mats, cushions and straw mats to sit on. In the Heian period in *shinden-zukuri 寝殿造 mansions, individual straw mats were common among the nobility. They were stored when not in use. From the Kamakura period, straw mats began to be laid over the entire floor area. During the Muromachi period, tatami mats were set closely together, and gradually became common. They were called shiki-datami 敷畳 in contrast to oki-datami 置畳 that meant a single mat-like cushion. A person's social status could be easily recognized by the thickness of the mats, the colors and patterns of the bindings of the tatami on which he sat. Tatami made in Kyoto are called kyōma-datami 京間畳 and tatami used in the country side are called inaka-datami 田舎畳. The former is 191 cm long, 95 cm wide and 5 cm thick; the latter is about 176 cm long, 88 cm wide and 5.5 cm thick. Long tatami may be 197 cm long × 7 cm thick.
Tatami in tea ceremony rooms *chashitsu 茶室 have special names. The host's mat may be called shudatami 主畳, *temae-datami 点前畳 or *dōgu-datami 道具畳. The tatami located where the host enters is called *fumikomi-datami 踏込畳. When the guest is a nobleman, he sits on a tatami mat called *kinin-datami 貴人畳. The seat for ordinary guests is called *kyaku-datami 客畳. The tatami in which the hearth is located is called *ro-datami 炉畳 and the mat for utensils is called dōgu-datami.