Paper used in furniture design. Watercolor paper has a long history of production and use. The thickness of paper is often measured by caliper, which is typically given in thousandths of an inch in the United States and in micrometers (µm) in the rest of the world. Paper may be between thick. Paper is often characterized by weight. In the United States, the weight assigned to a paper is the weight of a ream, 500 sheets, of varying "basic sizes", before the paper is cut into the size it is sold to end customers. For example, a ream of 20 lb,
Toilet paper human history dates back to the 6th century AD, in early medieval China. In 589 AD the scholar-official Yan Zhitui (531–591) wrote about the use of toilet paper: During the later Tang dynasty (618–907 AD), an Arab traveller to China in the year 851 AD remarked: During the early 14th century, it was recorded that in modern-day Zhejiang province alone there was an annual manufacturing of toilet paper amounting to ten million packages of 1,000 to 10,000 sheets of toilet paper each. During the Ming dynasty (1368–1644 AD), it was recorded in 1393 that an annual supply of 720,000 sheets