If you suffer from triskaidekaphobia, the 13th of every month is certainly not your day.
Triskaidekaphobia is the fear of the number 13. So, if you are a triskaidekaphobe and superstitious, Friday the 13th can be terrifying.
There’s a lot of folklore to buttress a triskaidekaphobe’s fear, and early examples date all the way back to the Bible.
Judas, the apostle known for betraying Jesus, is believed to be the 13th guest at the Last Supper. In addition, many people believe the Crucifixion of Jesus was on a Friday. Cain was also thought to have killed Abel on Friday the 13th.
In modern times, the horror film series "Friday the 13th" chronicles the activities of serial killer Jason Vorhees, his mother and their victims, of which there are many among the 12 movies.
There are some other spooky facts surrounding the number 13.
It is the number of witches necessary to make a coven. There’s also the infamous Apollo 13 moon mission.
Numerologists say 12 is a "complete" number, which means 13 is not. There are 12 Zodiac signs, 12 months in a year, and 12 tribes of Israel. The number 13 simply doesn’t complete things like the number 12 does.
Now, at least if you suffer from agoraphobia - the fear of certain places and situations - you'll know why days like today can be so frightening.
Emily DeCiccio is a video producer and writer for Fox Digital Originals. Follow her on Twitter @EmilyDeCiccio