Dates of the feasts
Roman Catholic and Anglican churches:
October 31 - Halloween, All Hallows’ Eve
November 1 - All Saints’ Day, All Hallows, Hallowmas, Solemnity of All Saints
November 2 - All Souls’ Day
The first Sunday after Pentecost - All Saints' Sunday, Council of All Saints
The Saturday before October 26 - Dedy, St.Dmitry’s Dedy, Soul Saturday, Demetrius Saturday
Image: "The Day of the Dead", 1859, by William-Adolphe Bouguereau (1825-1905), French painter.
Source: William-Adolphe Bouguereau [Public domain], via Wikimedia Commons: https://commons.wikimedia.org/wiki/File%3AWilliam-Adolphe_Bouguereau_(1825-1905)_-_The_Day_of_the_Dead_(1859).jpg
The holiday we know today as Halloween, a night of trick-or-treating by children and young people dressed in fantasy costumes, in reality dates back to one of the most ancient folk celebrations, a pagan festival of more than 2000 years ago commemorating the dead. The feast has survived over the centuries in popular traditions summoning influences of different cultures: from the Celtic festival of Samhain to Roman's Pomona Day, and to Christian holidays of All Saints and All Souls.
In Catholic and Anglican traditions the Days of the Dead are celebrated in the autumn period from October 31 to November 3, to remember and pray for those who have left this world. Looking back in time, we can recognize certain features and rituals of today celebrations in some pagan feasts. The most strong association with the world of the dead has the ancient festival of Samhain, some other fonts are connecting the tradition with the Roman pagan feast of Pomona.
Nowadays in the European countries the period of commemorating the dead lasts three days, beginning on October 31 with All Saints’ Eve, which was developed with time in American Halloween, the famous day of the witches, ghosts, dark powers, jack-o’-lanterns and trick-o-treating. The name “Halloween” derives from the word combination “All Hallows’ Eve” (All Saint’s Eve from Old English). By some sources, this evening is also dedicated to remembrance of the souls of damned.
November 1 is honouring All Saints, canonized and not, known and unknown.
Finally, November 2 closes the range of Hallowtide holidays, with commemoration of the souls being currently in Purgatory, who have not been purified yet and have not reached heaven. This day is known as All Souls' Day.
The Orthodox church has similar traditions of commemorating all dead and all Saints, spread over the year. All Saints' feast is celebrated on the first Sunday after Pentecost (or the 8th Sunday after Orthodox Easter), in honour of God and all Saints, known and unknown.
The Saturday before October 26 (the feast of Saint Demetrius of Thessaloniki) is called Demetrius Saturday, and is closely associated today with the ancient pagan tradition of “Dedy” – the remembrance of the dead relatives, which was transformed by the church into the Soul Saturday. It is one of the several dates in the year, devoted to commemoration and praying for the dead. The name of the ancient Dedy literally is translated as "Grandfathers", meaning all departed ancestors.