Halloween evolved from cultural and religious practices. The Ancient Celts believed that when summer turned to winter, or when the days had less daylight, the border between this world and the otherworld became thin, allowing spirits to pass between the world. To stop this from happening, they lit fires and wore costumes and masks for disguise and to ward them off. This festival was called Samhain, and is derived or from Old Irish and means “Summers End”
Ancient Britons also held a similar festival.
All Saints Day is a Catholic holiday, and was made in part to honour martyrs and the dead in the 7th century. Prior ro All Saints Day, many people used to honour the dead by holding rituals, not too disimilar to the Ancient Celts. This angered the Catholic Church who created All Saints Day to disuade people from practising in what they saw as an unholy ceromony.
In the nineteenth century, the festival had less religious and cultural significance and became more fun, with children taking part in such past times as trick or treat.