Jack-o-lanterns, costumes, trick-or-treating, pranks and apple bobbing are just a few of the traditions practiced around Halloween, but how did these get started?

Like two of our other most popular holidays, Christmas and Easter, Halloween has evolved much over the thousands of years it has been around.

Halloween has been around since before written history came to Europe, beginning as a Celtic-Druidic festival in preparation for the winter, called Samhain. By 1000 A.D the Catholic Church had designated Nov. 1 as All Saints Day (Alholowmesse in Middle English) and Nov. 2 as All Souls Day, commemorating the dead.

Over centuries these celebrations have merged into one—Halloween. Where did we get all of these unusual customs, though?

Costumes—The tradition of donning costumes goes all the way back to Samhain, when festival-goers wore costumes and masks to ensure that the restless spirits wouldn’t be able to recognize them. It was a well known fact that fairies often kidnapped those who took their fancy, but who would want to steal someone dressed as an ugly ghoul? Similarly, on All Saints Day attendees would dress up as saints, angels, and devils.

Apple Bobbing—The Romans celebrated Pomona, the goddess of fruit and trees, toward the end of October, and this probably contributed to Halloween imagery of pumpkins, corn husks and apples.

Trick-or-Treating—On All Saints Day and All Souls Day poor families would visit the houses of wealthier members of the community and receive ‘soul cakes’ in exchange for a promise to pray for the souls of the homeowner’s dead relatives. Eventually, this evolved into the practice of children going door to door and filling their baskets with candy. Nowadays, one quarter of all candy sold in the U.S. is for Halloween.

Halloween has spawned many peculiar customs, including young ladies in Ireland and Scotland throwing hazelnuts into a fire and apple peels over their shoulder to foretell the name of their future spouse. Halloween is rich with tradition, and that is what makes it so compelling to us today. It incorporates Celtic, Roman and Christian symbolism over thousands of years and is still celebrated by millions around the world.