May Day is the 1st of May, which in many countries is celebrated as a public holiday, especially as one in honour of working people. the first day of May, when left-wing political parties in some countries celebrate, and when people traditionally celebrate the arrival of spring. In Europe, the day (May 1) for traditional springtime celebrations. It probably originated in pre-Christian agricultural rituals. Celebrations included a May king and queen, a Maypole, and people carrying trees, green branches, or garlands. May Day was designated an international labour day by the International Socialist Congress of 1899, and it remains the standard Labour Day worldwide, with a few exceptions, including Canada and the U.S. A major holiday in the Soviet Union and other communist countries, it was the occasion for important political demonstrations