A folding screen consisting of multiple, joined panels. Folding screens vary in size; the standard size consists of six panels approximately 1.5 m high and 3.5 m wide. The term byōbu first appeared in records from Han dynasty China. Its original form is thought to be a free standing, single panel screen, which is now called tsuitate 衝立. One Han dynasty record defines byōbu as an object that prevents (byō or hei 屏) wind (bu or kaze 風) from blowing into a room. Folding screens comprised of multiple panels are a later innovation.
In Japan by the 8th century, folding screens were already in use as furnishings for the imperial court, especially at important ceremonies. The oldest extant examples are from the Nara period, preserved in the *Shōsōin 正倉院. In this period, screens generally consisted of six silk-covered panels that were connected to each other by leather or silk cords. The painting on each panel is individually framed by silk brocade. Each panel is then bound by a wood frame. In the Heian period, byōbu became indispensable as furniture in aristocratic residences and temples. The use of coin-shaped metal hinges, zenigata 銭形, later became a popular means of connecting panels. Byōbu produced by this technique are known as *zenigata byōbu 銭形屏風.
The byōbu format gained popularity around the Muromachi period, by which time screens were usually produced in pairs. By this time, too, byōbu were altered by the innovation of paper hinges; panels were linked by overlapping sheets of paper which were pasted over the joints of the panels. Each hinge was reinforced by additional strips of paper. This method of joining panels had the advantage of creating screens that were lighter, stronger at the joints, and easier to fold. When unfolded, this format produced a continuous, broad painting surface that was virtually uninterrupted at the vertical edges of each panel, which encouraged artists to expand a unified composition over all the panels and coincided with the taste in the Momoyama and early Edo periods for bold compositions in castle decoration. The use of gold backgrounds made with gold leaf, kinpaku 金箔, also developed at this time. In addition to screens of paper for supports, there are some variants made of woven bamboo, cypress wood panels, or reed. They were often decorated with paintings.
Special terms have been employed to count screens. The counter for panels most commonly used before the Muromachi period was sen 扇, and for a screen jō 畳, also written *jō 帖. A screen with six panels, rokusen 六扇, was counted as ichijō rokusen 一畳六扇. Today panels are counted with mai 枚, or kyoku 曲. The most commonly used number of panels are two, four, and six, thus resulting in screens called :
1) *nikyoku byōbu 二曲屏風 for a screen with two panels;
2) *yonkyoku byōbu 四曲屏風 for a screen with four panels;
3) *rokkyoku byōbu 六曲屏風 for a screen with six panels.
Since the Muromachi period, screens have been counted as a pair, calling each pair gu 具. In the Edo period, gu was replaced by sō 雙 (now written sō 双) such that a hansō 半雙 (also written 半双) means half a pair or one screen of the set. At the same time, seki 隻 came to refer to an independent screen, not part of a pair.
According to their function folding screens are also termed: *furosaki byōbu 風炉先屏風, *ga-no-byōbu 賀の屏風, *koshi byōbu 腰屏風, *makura byōbu 枕屏風, and *shiro-e byōbu 白絵屏風.