A Tokonoma is about the size of about one or a half tatami mat and is set into a wall of a Japanese-style room. This is a place to put up scrolls or display flower arrangements and of course bonsai.
The floor is made of wood and is one step higher than the rest of the room. Usually in the west the tokonoma build for bonsai display is higher than a step from the floor. But a tokonoma should be lower because it is the meaning that the viewer sits when he or she looks at the tokonoma or bends to see the display properly. This is the basic, but of course differences in culture and practical as well as aesthetical preferences may produce other measures and arrangements.
In the past, the tokonoma was a place where divinities were worshiped, but from the Muromachi (1392-1573) and the Azuchi-Momoyama Period (1573-1603) on it became a standard built-in feature with a decorative purpose. Recently, however in the average residence, there are many floor plans without tokonoma.
Tatami have been used since the Heian Period (794-1185). At that time they were laid out for the purpose of sitting. From the Muromachi Period (1392-1573) tatami mats also were used to cover the whole floor. Tatami mats are made of straw bundled in layers, stitched together and the surface is covered tightly with woven rushes.
A tatami mat measures about 90 x 180 cm, and the size of a Japanese room is expressed by its number of tatami mats.