Halloween is the most popular night related to witches, phantoms, spirits and generally with dark topics that usually scared people. We are used to watch movies related to this night and the only thing they explain is that in this night spirits of dead people wander on the street, I don't know what kind of purpose they have but it is supposed that they are not going to stroke us...
If you want to go out this night you need to dress up in any scaring costume: you can be Freddy Kruegger, a witch, a monster, a werewolf, vampire or whatever you want for one night. This is thought to be in order spirits not to recognize you and kill you.
Ok, the celebration is good, funny and we all enjoy dressing up like fantasy creatures and spending the night out with our friends. In Spain we still don't practice the "Trick or Treat" costume of the States but it is a matter of time. In fact, last year I remember some children knocking my father's door and saying "Trick or Treat!!". He gave them some chorizo slices and closed the door....
As I was saying, this costume is spreading all around the world, but the essence of it is something most of people don't really know.
Halloween comes from All Hallows Eve, which is the night before All Hallows Day on November 1st. This day people usually pay tribute to their dead relatives or their ancestors and this is why it is believed the night before the veil between the living and the death is thinner than any other day of the year. Lots of people try to contact with death people they miss. I have never tried but I don't thing our missed ones are nearer this night than any other. If they have passed out and reincarnate, you are not likely to contact with them and if they are spirits and protect you, they are every day by your side (or over your head, who knows?).
The thing is that Halloween is now rejected by the Catholic Church and many other religions but in old days it was broadly celebrated almost all over the world and it wasn't a satanist thing. Is a pagan celebration, but pagan only means natural, people connected with nature that believe and worship what they can see and feel. It is a celebration of the death of the year, the end of Witches year and yes, it is a night when you can pay tribute to your ancestors specially and make a ritual in their honor, talk with them and even put a plate for them in the table if it makes you feel near them, but I think you can do it whenever you want if you feel like it. Nowadays we are too inhibited by what other people are going to think or say but you should reconsider your mind. Please, be free, do what you want if you don't hurt anybody and then you'll realize you've reconnected with your essence. Because your essence is nature, we come from it and come back to it.