Samhain ( SAH-win, SOW-in, Irish: [ˈsˠəunʲ], Scottish Gaelic: [ˈs̪ãũ.ɪɲ]), Sauin (Manx: [ˈsoːɪnʲ]) or Oíche Shamhna ( EE-hə HOW-nə) is a Gaelic festival on 1 November marking the end of the harvest season and beginning of winter or "darker half" of the year. It is also the Irish language name for November. Celebrations begin on the evening of 31 October, since the Celtic day began and ended at sunset. This is about halfway between the autumnal equinox and winter solstice. It is one of the four Gaelic seasonal festivals along with Imbolc, Bealtaine, and Lughnasa. Historically it was widely observed throughout Ireland, Scotland, and the Isle of Man. A similar festival is held by the Brittonic Celtic people, called Calan Gaeaf in Wales. Samhain is believed to have Celtic pagan origins, and some Neolithic passage tombs in Ireland and Britain are aligned with the sunrise at the time of Samhain. It is mentioned in the earliest Irish literature, from the 9th century, and is associated with many important events in Irish mythology. The early literature says great gatherings and feasts marked Samhain when the ancient burial mounds were open, which were seen as portals to the Otherworld. Some of the literature also associates Samhain with bonfires and sacrifices. The festival was not recorded in detail until the early modern era. It was when cattle were brought down from the summer pastures and livestock were slaughtered. Special bonfires were lit, which were deemed to have protective and cleansing powers. Like Bealtaine, Samhain was a liminal or threshold festival, when the boundary between this world and the Otherworld blurred, making contact with the aos sí (the 'spirits' or 'fairies') more likely. Most scholars see them as remnants of pagan gods. At Samhain, they were appeased with offerings of food and drink to ensure the people and livestock survived the winter. The souls of dead kin were also thought to revisit their homes seeking hospitality, and a place was set at the table for them during a meal. Mumming and guising were part of the festival from at least the early modern era, whereby people went door-to-door in costume, reciting verses in exchange for food. The costumes may have been a way of imitating and disguising oneself from the aos sí. Divination was also a big part of the festival and often involved nuts and apples. In the late 19th century, John Rhys and James Frazer suggested it had been the "Celtic New Year", but that is disputed.In the 9th century, the Western Church endorsed 1 November as the date of All Saints' Day, possibly due to the influence of Alcuin, and 2 November later became All Souls' Day. It is believed that Samhain and All Saints'/All Souls' influenced each other and the modern Halloween. Most American Halloween traditions were inherited from Irish and Scottish immigrants. Folklorists have used the name 'Samhain' to refer to Gaelic 'Halloween' customs until the 19th century.Since the later 20th century Celtic neopagans and Wiccans have observed Samhain, or something based on it, as a religious holiday. Source: Wikipedia (en)