It is an ancient northern hemisphere spring festival. It is also a traditional spring holiday in many cultures. Dances, singing, and cake are usually part of the celebrations that the day includes.
In the late 19th century, May Day was chosen as the date for International Workers Day by the Socialists and Communists of the Second International to commemorate the Haymarket affair in Chicago. International Workers Day may also be referred to as May Day, but it is a different celebration from the traditional May Day.