To those who will celebrate.
May Day is May 1, and refers to any of several holidays celebrated on this day. May 1 was a traditional summer holiday in many pre-Christian European pagan cultures, and many elements of these holidays are still celebrated on May 1 today, such as the Maypole. While February 1 was the first day of Spring, May 1 was the first day of summer: hence, the summer solstice on June 25 (now the 22nd) was "midsummer."
Historically the Walpurgisnacht is derived from Pagan spring customs, where the arrival of spring was celebrated with bonfires at night. Viking fertility celebrations took place around February 25 and due to Walburga being declared a saint at that time of year, her name became associated with the celebrations. Walburga was honored in the same way that Vikings had celebrated spring and as they spread throughout Europe, the two dates became mixed together and created the Walpurgis Night celebration. The main mascot of Walpurgis Day is the witch.