billion per year.

Production
Production and processing of nori by current methods is a highly advanced form of agriculture. The biology of Porphyra, although complicated, is well understood and this knowledge is used to control virtually every step of the production process. Farming takes place in the sea where the Porphyra plants grow attached to nets suspended at the sea surface and where the farmers operate from boats. The plants grow rapidly, requiring about 45 days from "seeding" until the first harvest. Multiple harvests can be taken from a single seeding, typically at about 10 day intervals. Harvesting is accomplished using mechanical harvesters of a variety of configurations. Processing of raw product is mostly accomplished by highly automated machines that accurately duplicate traditional manual processing steps, but with much improved efficiency and consistency. The final product is a paper thin, dark, black, dried sheet of approximately 18 X 20 cm and 3 grams in weight. The nori sheet was invented in Asakusa, Edo (former Tokyo) in Edo period by the method of Japanese papers.

Nori is commonly used as a wrap for sushi (makizushi) and rice balls (onigiri). It is also a common garnish or flavoring in noodle preparations and soups. Nori is most typically toasted prior to consumption ("yaki-nori" in Japanese). A very common and popular secondary product is toasted and flavored nori ("ajitsuke-nori" in Japanese), in which a flavoring mixture (variable, but typically soy sauce, spices and sugar in the Japanese style or sesame oil and salt in the Korean style) is applied in combination with the toasting process. Nori is also eaten by making it into a soy sauce flavored paste noritsukudani (in Japanese).

A related product, prepared from the unrelated green algae Monostroma and Enteromorpha, is called aonori (in Japanese, literally green nori), and is used like herbs on everyday meals like okonomiyaki and yakisoba.Nori is sometimes called laver in English, and laver is eaten as laverbread in a savory oatmeal in Wales and Ireland. Laver usually applies to plants of the genus Porphyra and not to the finished edible sheets of nori. The English term is not well known, and in the U.S., the term nori is more common.