Halloween. So called because it is the e'en (evening) before All Hallows (or All Saints) day.
There is a common misconception that the 'trick or treat' custom is of American origin. It isn't. It was almost certainly a Celtic activity which was exported across the Atlantic where it was well received. The name for the custom in Scotland and Ireland is 'guising' because children go from door to door disguised in costumes to ask for a treat on threat of retribution if one isn't received.
It's a bit of fun and kids love it. The trouble is that many grown-ups don't - especially older ones who find it intrusive, annoying and in some cases genuinely frightening.
This can be problematic. Excited youngsters get all dressed up and roam the streets knocking on doors to ask for sweets but may find the door answered by a very cross adult shouting at them to go away.
There is a simple solution. If you are happy for the kids to call, put a sign up to tell them so, a pumpkin outside the door perhaps, or simply put on a welcoming outside light. Alternatively leave some sweets outside for them to help themselves to.
If you don't want them to call, leave the front of your house in darkness.
If you're the parents of the trick or treat kids, tell them only to call at the welcoming doors. Explain to them that the houses in darkness are where the witches and monsters live who turn children into black cats which they keep in cages and feed pieces of dead rats to.
That should do it.