Halloween tradition on U.S.A

In medieval times, one popular All Souls' Day practice was to make "soul cakes," simple bread desserts with a currant topping. In a custom called "souling," children would go door-to-door begging for the cakes, much like modern trick-or-treaters. For every cake a child collected, he or she would have to say a prayer for the dead relatives of the person who gave the cake. These prayers would help the relatives find their way out of purgatory and into heaven. The children even sang a soul cake song along the lines of the modern "Trick-or-treat, trick-or-treat, give me something good to eat." One version of the song went:

A soul cake!
A soul cake!
Have mercy on all Christian souls, for
A soul cake!

Today, for children, dressing up and trick-or-treating door-to-door is still the main event. Most households in the United States participate. Many adults dress up themselves, to go out with their children or to attend costume parties and contests.
Halloween continues to be extremely popular with kids of all ages; 85 to 90 percent of U.S. children go trick-or-treating or engage in other Halloween festivities every year, and many adults also join in on the fun.

on: http://people.howstuffworks.com/halloween7.htm
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