Samhain was one of four seasonal festivals, the others being Beltane, Imbolc, and Lughnasadh, and was thought to have been one of the most important festivals of the year. Contrary to popular belief, Samhain is not a celebration of the Celtic god of the dead, and instead celebrates the end of the harvest season and the beginning of winter.
It is traditionally celebrated on 31 October/1st November and is believed to be the night where the veil between the living and the dead is especially thin and communication with spirit is therefore easier. It is a time to honour and remember family members, friends and pets who have passed away.
As the boundary between this world and the next can be crossed more easily it means that spirits and fairies can more easily come into our world. The souls of the dead are also thought to revisit their homes seeking hospitality and so feasts are arranged to welcome them. Bonfires are lit and there is much merriment and celebration.