Tatami - wood
Tatami mats are thick, woven straw mats that measure about one by two meters in size. Originally a luxury that only the wealthy could afford, tatami gradually became more common and can now be found in virtually all traditional Japanese homes. Tatami mats have been so integral to Japanese homes, that the size of rooms in Japan is commonly measured by the number of mats that would fit it, e.g. an 8-mat room. Note that footwear - even slippers - should be removed before stepping onto tatami.