A fair is a gathering of people to display or trade produce or other goods, to parade or display animals and often to enjoy associated carnival or funfair entertainment. It is normally of the essence of a fair that it is temporary; some last only an afternoon while others may last as long as ten weeks. Activities at fairs vary widely. Some trade fairs are important regular business events either where products are traded between businesspeople, as at the Frankfurt Book Fair, where publishers sell book rights in other markets to other publishers, or where products are showcased to consumers, as for example in agricultural districts where they present opportunities to display and demonstrate the latest machinery on the market to farmers. Fairs are also known by many different names around the world, such as agricultural show, fte, county fair, exhibition or state fair, festival, market and show. Flea markets and auto shows are sometimes incorporated into a fair.