Significance
Baisakhi is the Punjabi spring harvest festival and, for Sikhs, one of the holiest days — commemorating the founding of the Khalsa Panth by Guru Gobind Singh in 1699. It also marks the solar new year in many regions.
For farmers it is a joyous thanksgiving for the ripened rabi harvest.
Rituals
Sikhs visit gurdwaras, take part in Nagar Kirtan processions and langar. In the fields, people celebrate the harvest with energetic bhangra and gidda, folk music and fairs. The Golden Temple sees special congregations.
How the date is fixed
Baisakhi is a solar festival, falling when the Sun enters Aries (Mesha Sankranti) — around 13–14 April each year — so its date is nearly fixed.