Vaisakhi, also known as Baisakhi, Vaishakhi, or Vasakhi is a historical and religious festival in Sikhism. It is usually celebrated on April 13 or 14 every year.
Vaisakhi marks the Sikh new year. It is additionally a spring harvest festival for the Sikhs. Vaisakhi is an ancient festival of Hindus, marking the Solar New Year and also celebrating the spring harvest. It marks the sacredness of rivers in Hindu culture, it is regionally known by many names, but celebrated in broadly similar ways.
Source: Wikipedia