The main event of Halloween is trick-or-treating, also known as guising in Scotland, in which children dress up in costume
disguises and go door-to-door in their neighborhood, ringing the bell and yelling "trick or treat!" (or, less frequently,
"Halloween apples!") The occupants of the house (who might themselves dress in a scary costume) will then hand out
small candies, miniature chocolate bars or other treats. Some parents opt to give "healthy" treats, such as small
boxes of raisins, but this practice does not please the children. Homes sometimes use sound effects and fog machines to help
set a spooky mood. Other house decoration themes (that are less scary) are used to entertain younger visitors. Children can
often accumulate many treats on Halloween night, filling up entire pillow cases or shopping bags.
In Scotland children or guisers will have to impress the members of the houses they visit with a song, trick, joke or
dance in order to earn their treats.
Tricks play less of a role in modern Halloween, though the night before Halloween is often marked by pranks such as soaping
windows, egging houses or stringing toilet paper through trees. Before indoor plumbing was so widespread, tipping over or
displacing outhouses was a popular form of trick.
Typical Halloween costumes have traditionally been monsters such as vampires, ghosts, witches, and devils. The stereotypical
Halloween costume is a sheet with eyeholes cut in it as a ghost costume. In nineteenth-century Scotland and Ireland the reason
for wearing such fearsome (and non-fearsome) costumes was the belief that since the spirits that were abroad that night were
essentially intent on doing harm, the best way to avoid this was to fool the spirits into believing that you were one of them.
In recent years, it has become common for costumes to be based on themes other than traditional horror, such as dressing up
as a character from a TV show or movie. In 2001, after the September 11 attacks, for example, costumes of firefighters, police
officers, and United States military personnel became popular among children. In 2004, an estimated 2.15 million children
in the United States were expected to dress up as Spider-Man, the year's most popular costume.  (http://www.nrf.com/content/default.asp?folder=press/release2004&file=costumes1004.htm&bhcp=1)
A program started by UNICEF involves the distribution of small boxes by schools to trick-or-treaters, in which they can
collect small change from the houses they visit for donation to the charity.
BIGresearch conducted a survey for the National Retail Federation in the US and found that 54.1 percent of consumers planned
to buy a costume for Halloween 2004, spending $28.11 on average. An estimate of $3.12 billion was made for the holiday spending.
A child usually "grows out of" trick-or-treating by his or her teenage years. Teenagers and adults instead often
celebrate Halloween with costume parties or other social get-togethers.