The International Mathematical Olympiad (IMO) is the World Championship Mathematics Competition for High School students and is held each year in a different country. The first IMO was held in 1959 in Romania, with seven countries participating. It has gradually expanded to over 100 countries from all seven continents. IMO2023 should be the largest ever, with participants expected from 110 countries. The IMO Board ensures that the competition takes place each year and that each host country observes the regulations and traditions of the IMO.