Trick-or-treating is a traditional Halloween activity, wherein children go from house to house and ask for a treat with the idle threat of pranking the homeowners otherwise. Even while tricks are widely discouraged, most houses provide free treats in the form of candy or novelty toys.
Trick-or-treating declined in the late 1970s and early 1980s because of the tainted candy scare that warned of poison and razor blades in distributed treats. Hospitals got involved, offering free X-rays of Halloween candy. The scare was an urban legend that has been debunked to the return of trick-or-treating.
The concept of trick-or-treating probably dates back to the early All Souls' Day parades in England. During the festivities, poor citizens would beg for food and families would give them pastries called "soul cakes" in return for their promise to pray for the family's dead relatives. The distribution of soul cakes was encouraged by the church as a way to replace the ancient practice of leaving food and wine for the returning spirits on Halloween night. The practice, which was referred to as "going-a-souling" was eventually taken up by children who would visit the houses in their neighbourhood and be given ale, food, and money.
The tradition of dressing in costumes and masks on Halloween finds its roots in both European and Celtic history. On Halloween, when it was believed that ghosts came back to the earthly realm, people thought they would encounter the ghosts if they left their homes. Therefore, to avoid being seen by these ghosts, people would wear masks when they left their homes after dark so that the ghosts would mistake them for fellow spirits.
In North America, the practice of trick-or-treating dates to the late 1920s.
Treats
Candy should be wrapped. In general, due to safety issues, children are not allowed to eat candy from people they do not know that is not still in the original manufacturer's sealed containers or appears unwrapped.
Candy corn, considered one of the icons of the Halloween celebration, is a popular treat.
Other treats
Instead of candy, you can give out "party favour" type items. For instance, in some places, you can buy packages of small Play-Doh containers—each only costs 20-30 cents. Many stores sell Halloween themed party favours, like plastic yo-yos, small bouncy balls or fake vampire fangs.
Tricks
If no treats are received, the visitors may try to pull pranks on the people's houses to trick them. Well-known pranks include covering people's property with toilet-paper, smearing soap o windows or throwing flour or eggs at houses, all of which are forms of vandalism.
Would-be tricksters should keep in mind that egging a person's house or car can cause permanent damage to the paint job if not taken care of immediately, with a belief that it can cause more harm in colder environments due to the freezing effect. As eggs are organic, it will also leave a rotting smell as the egg decays over time.
Some homeowners use an alternate interpretation of the phrase "trick-or-treat", choosing the trick option, which is not traditionally implied as an option for the homeowners. They will then perform a magic trick for the trick-or-treaters.