May Day occurs on May 1st and refers to several public holidays. In many countries, May Day is synonymous with International Workers' Day, or Labour Day, a day of political demonstrations and celebrations organised by unions and other groups. May Day is also a traditional holiday in many cultures.
May Day can refer to various labour celebrations conducted on May 1st that commemorate the fight for the eight-hour day. May Day in this regard is called International Workers' Day, or Labour Day. The idea for a "workers holiday" began in Australia in 1856; after a Stonemason's victory, April 22nd was "Eight-Hour Day", a public holiday. With the idea having spread around the world, the choice of May 1st became a commemoration by the Second International for the people involved in the 1886 Haymarket affair.
May Day is related to the Celtic festival of Beltane and the Germanic festival of Walpurgis Night. May Day falls exactly half a year from November 1, another cross-quarter day which is also associated with various northern European pagan and neopagan festivals such as Samhain. May Day marks the end of the winter half of the year in the Northern hemisphere, and it has traditionally been an occasion for popular and often raucous celebrations.
As Europe became Christianized, the pagan holidays either lost their religious character and became popular secular celebrations, as with May Day, or they were merged with or replaced by new Christian holidays such as Christmas, Easter and All Saints' Day. In the 20th Century many neopagans began reconstructing the old traditions and celebrating May Day as a pagan religious festival again. (From: Wikipedia)