Due to the popularity of these events, in 1920 the creation and organisation of these events lead to the formation of the ‘Bureau International des Expositions’ (BIE) or in English ‘International Exhibitions Bureau’ thus leading to a party to help control quality and frequency of the events. The events are split into two types, registered and recognised with registered being the largest and the interval between registered events is 5 years but last for 6 months at a time, the current being Expo 2015 in Milan, and the one to follow Expo 2020 in Dubai.
