International exhibitions in the 19th Century were categorized่[*] as follows:
Industrial Exhibitions comprised fairs with specific contents relating to specialized industries, or round-ups of industrial advances in a participating country or region.
International Trade Fairs organized by a host country to commemorate an historical milestone; for example, the Philadelphia Expo which celebrated the Centennial of American Independence and the July 4, 1776 Declaration.
International Trade Fairs with participation from several exhibiting nations, such as The Great Exhibition of London, 1851.
