It's the first week of October, which means it's officially acceptable to start thinking about Halloween.
But the annual celebration has a history that stems back much further than you might think.
Here is everything you need to know about the seasonal event and its origins.
When is Halloween?
Historically, Halloween comes one day before the Christian holy day All Hallows' Day, also known as All Saints' or Hallowmas - which was observed on November 1 and 2.
Halloween was, and still is, observed on the same date each year, October 31.
This is because, historians believe it originates from an ancient Celtic festival called Samhain, which marked the end of the harvest season.
Why do we celebrate Halloween?
When celebrating Samhain, people would light bonfires and wear costumes to ward off ghosts. This mainly happened in Ireland, Scotland and the Isle of Man.
As well as marking the end of a season, observers also believed that the boundaries between this world and the supernatural world became closer, allowing them to connect with the dead.
Dead humans were also said to revisit their former homes.
Why do we carve pumpkins during Halloween?
The Pagans would connect with the spirits through ritualistic ceremonies including costumes, special feasts and making lanterns.
They would make the lanterns by hollowing out large fruits. Historians believe that this is where the modern-day idea of the Jack-o-lantern comes from.
In the UK and Ireland, vegetables such as turnips, beets and potatoes were used at first.
In the USA, Irish immigrants began to hollow out pumpkins instead, as they were much softer to carve. It is now the preferred choice of vegetable for the occasion.
Why do we go trick or treating?
Trick or treating began in the middle ages when young children would go door-to-door asking for food or money in exchange for songs and prayers, often said on behalf of the dead.
The act was referred to as 'souling' and the children were called 'soulers'.
Meanwhile, the earliest known reference of the term 'trick or treat' dates back to 1927 when it was printed in an edition of the Blackie, Alberta Canada Herald.