A world's fair, world fair, world exposition, or universal exposition (sometimes expo or Expo for short) is a large public exhibition. These exhibitions vary in character and are held in varying parts of the world. The next world's fair is Expo 2017 and is to be held in Astana, Kazakhstan.

Since the 1928 Convention Relating to International Exhibitions came into force, the Bureau International des Expositions (BIE; English: International Exhibitions Bureau) has served as an international sanctioning body for world's fairs. BIE-approved fairs are of three types: universal, international, and specialized.

More Info: en.wikipedia.org