Ochi Day, also known as Ohi Day, is observed every October 28 in Greece, Cyprus, and Greek communities worldwide. This national holiday commemorates the events of October 28, 1940, when Greek Prime Minister Ioannis Metaxas responded to an Italian ultimatum with a decisive "όχι" ("No!"), leading to Italy's invasion of Greece and the country's involvement in World War II. The day is marked by public celebrations, including student and military parades, and buildings are adorned with national flags. The anniversary of this refusal has been celebrated as Ochi Day since the end of the war, symbolizing Greek resistance and national pride.