Does anyone know how it originated or what it represents?
Halloween = All Hallows' Eve, the eve of All Saints' Day which is November 1. A time of pagan festivities. It originates from the celtic festival of Samhain. The word, Samhain, means "the god of the dead. The Celts believed that the border between this world and the otherworld became thin on Sanhain, allowing spirits to pass through. It is the night during which the division between the world of the living and the other world was blurred so spirits of the dead and inhabitants from the underworld were able to walk free on the earth. It was believed necessary to dress as a spirit or otherworldly creature when venturing outdoors to blend in, and this is where dressing in such a manner for Halloween comes from.
Also known as "the day of the dead".
Costumes, lanterns, trick or treat, pumpkin carving, bonfires and more.... each one of these traditions has it's origins in a pagan ritual that has evolved into today's activities.
Now, the church decided to establish All Saints day on November 1, so that the eve, October 31, would be the beginning of honoring saints. Incorporating pagan holidays into the "christain" calendar was simply a method for the Roman Catholic church to convert the pagans. Pope Gregory the First said in 601AD, - if a group of people worshiped a tree, rather than cut it down, consecrate it to Christ and allow it's continued worship.
All Saints day was a celebration of the start of a new cycle of fertility for the celtic Goddess Eiseria. So that, in itself, is also pagan.
If you don't do the research, then you will think it's just another "fun" holiday. But if you do the research, you will know that this is yet another pagan holiday and should not be observed by anyone who believes that Jesus is the Messiah.