The first of May is celebrated in the Northern Hemisphere and it is celebrated by many different countries and religions. It is a day of many different holidays.
May Day is related to the Celtic pagan festival of Beltane and the Germanic festival of Walpurgis Night. May 1st was the first day of summer and the summer solstice (June 21st) was Midsummer. May Day was changed into a secular holiday after Europe's Christianization. Roman Catholics celebrate May as 'Mary's month' and May Day is usually a celebration of the Blessed Virgin Mary.
May Day is still observed in many countries today with dancing, the crowning of the May Queen and celebrations involving a Maypole in which dancers circle a pole with ribbons.
Did you know that May 1st is also U.S. Law Day which emphasizes the role of law in the foundation of the country and its importance for society. It is not a well-known holiday.