Here's how Halloween went from a day of demons and turnips to a festival of costumes and candy

• Halloween draws from both Celtic and Christian traditions.

• While it's always had a morbid, spooky vibe, the festivities have changed quite a lot over the centuries.

Halloween is the spookiest night of the year.

It's also a boon to the retail industry. In the US, spending on costumes and candy may reach a record high this year, Business Insider reported.

And the Halloween fever isn't contained to the States, either. In fact, people around the world celebrate the holiday in many different ways.

But where did all these strange practices come from? Turns out, a lot of these customs date back centuries. The holiday has changed over time, transforming from an ancient tradition to the flashy fright-fest we know and love today.

Let's take a look at the origins of some of our favorite Halloween traditions: