Trick or treat is an American custom, but it has its origins in earlier customs: “guising”, which was practiced in Scotland and Ireland; and “souling”, which was practiced in Britain and Ireland, but is more usually associated with England.

In “guising”, children wore costumes (or “guises”), and went from door to door, much like with trick or treat. The main difference was that children who went guising had to perform something - a joke, a song, or a poem - to receive a treat.

“Souling” involved people going in groups, offering to pray for the souls of family members of the people they visited: for this, they would receive a “soul cake”.

“Trick or treat” is usually just something that people say - these days, people don’t usually expect to have to play a trick - but in the 1990s, egging (throwing raw eggs) and TP-ing (throwing an opened roll of toilet paper, to “decorate” the house) were common “tricks”.