exhibition held every two years, often intending to gather together the best of international art; there are now many of these. A travelling exhibition is an exhibition seen at several venues, sometimes across the world. Exhibitions of new or recent art can be juried, invitational, or open. A juried exhibition, such as the Royal Academy Summer Exhibition in London, or the Iowa Biennial, has an individual (or group) acting as judge of the submitted artworks, selecting which are to be shown. If prizes are to be awarded, the judge or panel of judges will usually select the prizewinners as well. In an invitational exhibition, such as the Whitney Biennial, the organizer of the show asks certain artists to supply artworks and exhibits them. An open or "non-juried" exhibition, such as the Kyoto Triennial, allows anybody to enter artworks and shows them all. A type of exhibition that is usually non-juried is a mail art exhibition. History The art exhibition has played a crucial part in the market for new art since the 18th and 19th centuries. The Paris Salon, open to the public from 1737, rapidly became the key factor in determining the reputation, and so the price, of the French artists of the day. The Royal Academy in London, beginning in 1769, soon established a similar grip on the market, and in both countries artists put great efforts into making pictures that would be a success, often changing the direction of their style to meet popular or critical taste. The British Institution was added to the London scene in 1805, holding two annual exhibitions, one of new British art for sale, and one of loans from the collections of its aristocratic patrons. These exhibitions received lengthy and detailed reviews in the press, which were the main vehicle for the art criticism of the day. Critics as distinguished as Denis Diderot and John Ruskin held their readers attention by sharply divergent reviews of different works, praising some extravagantly and giving others the most savage put-downs they could think of. Many of the works were already sold, but success at these exhibitions was a crucial way for an artist to attract more commissions. Among important early one-off loan exhibitions of older paintings were the Art Treasures Exhibition, Manchester 1857, and the Exhibition of National Portraits in London, at what is now the Victoria and Albert Museum, held in three stages in