The Expo is a non-commercial Universal Exposition (not a trade fair) organized by the nation which wins the candidature, with other countries participating through the diplomatic channels of the hosting nation.
The first Expo was held in London in 1851 and was such a success that other nations were encouraged to organize similar events like the Paris Expo in 1889 for which the Eiffel Tower was designed and built.
Each Expo has a universal theme and is held in an area which has been masterminded as a place of exchange and encounter to promote a unique experience for participants and visitors who discover and experiment with the theme. More than displaying major technological novelties the Expo’s role is oriented towards interpreting the collective challenges to which mankind is asked to respond.
The international organization which regulates the frequency, quality and progress of the event is the Bureau International des Expositions (BIE) set up under an international convention which was signed in Paris in 1928. Currently some 157 nations are BIE members.