What is may day?

Where is it celebrated and why? I'm under the impression that May Day celebrated in Latin American countries, but not sure. Can anyone explain the origins and meaning behind May Day? Thanks.

May Day is actually a dual celebration. May 1st is celebrated as the first day of Summer and customs like dancing around a maypole go all the way back to pre-Christian pagan celebrations. It is also a day to promote labor and celebrate advances in the labor movement and in some places is known as International Worker's Day. In America it May Day was perceived as a Communist celebration so to to discourage its celebration May 1 was designated as "Law Day" and "Loyalty Day" in the 1950's (the same decade when "one nation under God" was added to the pledge of allegience and our national motto was changed from the inclusive "E Pluribus Unum" to the exclusive "In God We Trust). May 1 is Labor day in most countries but in America to seperate it from May Day Labor day is celebrated on the first Monday of September.

I didn't know the answer to this either so I googled it and this is what I came up with.

http://www.theholidayspot.com/mayday/history.htm

May Day: http://en.wikipedia.org/wiki/May_day

The first day of the month of May is often called May Day. It's a celebration of many events. It is declared as the national holiday in many countries all over the world. It is the celebration of Spring, a day for organized labors, a day of political protest, a neopagan festival, and a saint's feast day.

http://www.123greetings.com/events/may_day/
http://www.theholidayspot.com/mayday/history.htm